There are a few different types of bass strings available, flatwound, roundwound and half round.
Flatwound strings have the mellowest tone of all the string types. They are made with a flat wire wound around a core wire. The core wire goes from the top end of the string and goes around the ball end. They have the smoothest feel and are easier on the frets than the other two types of strings, as well as being a bit easier on fingerboards of fretless basses. These strings were used on all bass guitars through the 50's, and 60's. Although round wound strings started becoming popular in the 70's, new bass guitars came with factory installed flatwound strings. Flatwound strings lost popularity as the bass started coming out of the background to the forefront of music. Flatwound strings remained popular with bassists that play blues and traditional jazz. In recent years, flatwound strings have become a bit more popular in all types of music as bassists look to find different tones for their music.
Round wound strings are brighter than flatwound strings. They are made with a round wire, wound around a core wire. These strings make more finger noise and can wear frets faster than flatwound strings. Roundwound strings have become more popular than flatwound strings due to their brightness.
There are roundwound strings wound with nickel wire and there and also roundwound strings wrapped with stainless steel wire. Stainless steel wound strings are the brightest and loudest of all the strings. They also make the most noise and are the hardest on frets. Stainless steel wound strings are popular with many bassists in loud rock bands, due to the power and brilliance they have. There are also nickel plated stainless steel wound strings (NPS). The attributes of NPS strings will fall in between those of stainless steel wound and nickel wound strings.
Halfwound, groundwound or pressurewound strings start out as roundwound strings and then are either run through rollers which press the outer part of the string or ground a bit to make the outside a bit flatter. This way the string will produce less finger noise, be easier on the frets and have a good amount of the brightness that roundwound strings have.
Some of the string manufacturers put silk wrap on the ends of their bass strings. This is to keep the windings at the ends of the strings from separating. Bass strings that do not have the silk wrap on the ends are made using a method of winding the ends so that they do not separate, therefore the silk wrap is not necessary and helps keep the cost of the strings lower. Some bassists prefer to use strings that have silk wrapped ends, because they like the way it looks and they feel it protects the tuning posts from the strings.

Although the properties of the different string types can make a difference in fret wear, finger noise, brightness and power, your playing style is also a big factor in how much of each is produced. If you and heavy handed with your fretting hand and picking attack, you can wear out frets with any type of strings and produce a fair amount of finger noise. Your choice of string should be based on your playing style, preference of sound and feel and the style of music you play.

How quickly your strings lose the new sound depends on how much you play your bass, how you maintain it and your personal hand sweat chemistry. Bassists who gig and or rehearse regularly with a band will go through strings faster than bassists who play for the fun of it at home. There are bassists that boil their used bass strings in a pot of water to renew the bright sound they had when they were new. There is an article on the internet about building a tube using PVC pipe and filling it with denatured alcohol to renew the sound of the strings. Both of these procedures are used to clean the strings of sweat, dirt and contaminants that get into the windings of the strings. Each of these methods of cleaning the strings will work to extend the like of your strings to some extent. You might not have the original brightness nor have the brightness for as long as the time it between when you first installed the strings, to when you to boiled them or soaked them in a tube filled with alcohol.
Here is an alternative that I use, which will work as long as you don't wait until too much of the brightness has already been lost. I prefer to just keep the sweat, dirt and other contaminants to a minimum for as long as I can. When I am finished playing my bass, I wipe down the strings with a soft, clean and dry cloth. When I feel the strings are starting to lose some of their brightness (long before they sound dull), I wipe them down with some alcohol or even better, naphtha on a small piece of soft cloth. I do this by cutting up some small pieces of cloth, smaller than 2" x 2". I prefer to use chamois cloth to do this. I cut open a clean, smooth plastic bag to put in between the strings and the body and neck of the bass to keep alcohol and small cloth fibers from the bass. Next, I detune the string I want to clean, so I can get the whole string easier. I apply some 90% isopropyl alcohol to the chamois cloth and with a moderately firm grip, wipe the entire length of the string several times, using a different part of the piece of cloth each time. The dirt that comes off is usually visible on the cloth. When I don't any more see more dirt coming off the string and onto the chamois cloth, I wipe the length of the string with a clean, soft and dry cloth or towel. I tune the string to pitch and go on to do the same to the rest of the strings. You can do this cleaning to your strings when you feel the need to, with a minimal amount of time and materials.
If you decide to boil the strings, use a pot that that won't be used for cooking so your mother or wife doesn't lose it on you. When you have removed the strings from your bass, coil them up like when they were new in their package. Place the strings in the water after it has started to boil. Don't add salt to the water to make it boil sooner! Boil the strings for about 15 minutes. Pour the water out of the pot, then carefully remove the hot bass strings and put them on a towel. Give them a minute or two to cool, then dry them thoroughly with a clean, dry cloth. Be sure the strings are completely dry before reinstalling them on your bass. You might want to put them in an oven at a low heat setting to make sure they dry well quickly to avoid having them rust.
Unless you have a bridge with a quick hook design on your bass, uninstalling and reinstalling bass strings can weaken and maybe break the ends of the strings that wind around the machine head posts, especially silk end wrapped strings, so you might not want to boil or soak your strings too many times. No matter how you try to keep your strings clean, eventually little or none of the original sound can be restored and it will be time to change them.
There are products available in some music stores that you can apply to you new bass strings which are made to coat and protect your new, unused strings, similar to the coatings that D'Addario and Elixir put on their coated strings. The coating keeps the dirt out of the winding. I have not yet tried this aftermarket string coating, so I cannot say how well they work and whether or not it will affect string performance. There are some sets of strings priced for bassists on a tight budget. Some bassists prefer the sound of old strings.

Machine heads with open backs are exposed to the elements. Dirt and contaminants get in the parts and can stop the key from turning smoothly. The open type can be disassembled by removing the large screw in the center of the sprocket gear, Remove the screw, washer and gear. The post of the tuner should come out through the bushing in front of the headstock. Some machine heads might have a spacer between the sprocket gear and the plate as seen on the third picture below. There is usually no need to remove the bushing or main part of the tuner. Clean all of the parts well with a penetrating oil, including the inside of the bushing and in the grooves of the worm gear side of the key shaft, removing dirt, corrosion and old gummed up grease. Wipe off the excess penetrating oil. The residual coating of oil will protect the parts from corrosion. As you reassemble the machine head, you can put a tiny dab of white grease on the metal to metal moving parts. (the part of the post that contacts the bushing, the side of the sprocket gear that contacts the plate of the machine head), to help the smoothness of the operation. You will notice that the bottom of the post is shaped to fit into only one side of the sprocket gear.

Soldering is easy when you know how to do it properly. To wire a guitar or to do soldering on a circuit board, rosin core solder with a 60/40 tin-lead alloy should be used. You should use a 15 to 40 watt soldering iron. The soldering iron should be in good condition. It's AC wire should not have any tangles, burns or cuts in it and the tip should not be crusty, worn or oxidized. Solder in a ventilated room. This type of solder rarely spits up like types of solder used with liquid flux can, but don't take a chance, wear goggles to protect your eyes! The larger, higher wattage, gun shaped soldering irons work well, but they may be too powerful for sensitive components, especially if you've had little or no experience soldering. For safety and convenience, use a soldering iron stand to hold the iron when it's hot and you are preparing to solder. These help keep you from accidentally burning something or grabbing the wrong end of the iron, which is NOT fun and may severely burn your hand, putting your bass playing amongst other things on hold for a bit. The base of the holder should have an area to hold a wet sponge that you will use to clean the tip of the iron that has excess solder or solder has has been hot too long. The size and shape of the tip should correspond with the size of the solder joint you will make. The tips are replaceable, change the tip as necessary. Small solder points will need a pencil point tip, larger solder points will need a chisel shaped tip. Before you plug the soldering iron into the AC outlet, take about an inch or two of solder and tightly wrap it several times around the tip of the iron. This will "tin" the tip, helping the solder melt and flow easier. This will also help the tip last longer. When the solder melts off the tip, you'll know the iron is ready to use. Solder flows and hardens to where the heat is transferred. You always want the tip to look shiny and wet when you are using the iron. If the surface that the solder needs to be on has not been heated well, the solder will only stay on the iron tip and / or you might make a cold solder joint, which may work intermittently or not at all. For best results, first wipe the tip of the iron on the wet sponge. Touch the iron tip to the area where the solder is needed, then touch the solder to the tip and solder joint. Let the solder flow on to the solder joint, then pull the iron away. Do not use an excessive amount of solder, just enough to make the parts hold. When you are finished soldering the connection, wipe the tip of the iron on the wet sponge to clean it. Sometimes getting the existing solder on a potentiometer to melt is difficult. To make it much easier, melt a little new solder onto the old solder, that will get the existing solder to melt. When you are finished using the soldering iron, unplug it and wipe the tip on the sponge while it is still hot. Never leave a hot iron unattended.

A note about those COLD HEAT soldering irons. They are convenient tools, but only meant to handle small, quick solder applications. They are not meant to solder ground wires onto the backs of potentiometers or other solder points that will take longer than a momentary touch to form. They work well on small wire connections and most standard circuit boards. There is also a difference to the technique of soldering with them due to their design and function.

String Tension: You may be advised by airline personnel to be sure to detune your bass before air travel. Do not take this advice, leave your bass in tune. Your bass was designed to handle string tension at all times. Guitar manufacturers ship their guitars fully tuned to music stores and they arrive just fine. Airline companies fly airplanes, they don't build guitars. If an airline worker at the airport asks you if you've already detuned your guitar, just say yes to avoid the ridiculous lecture. If you intend to do any air travel with your bass, be sure to buy it a flight case. The chances of carrying your bass onboard an airplane are extremely small unless you have purchased an extra seat for it. Even if you were allowed to take it onboard as personal luggage one time, you might not be able to take it onboard the next time, even if it is the same airline. The case for air travel should be an ATA approved fight case. Baggage handlers are moving baggage in and out of planes quickly, so they are unlikely to always be gentle with your case. The right case will hold up to rough handling and other cargo that it rides with.

Taking Your Bass On An Airplane: It is very uncommon for a bassist to be allowed to bring his or her bass guitar into the cabin of an airplane. The people at the airport will tell you that it is too big. The only way to ensure that you will be able to bring it on board, is to buy a seat for it. I've found that the best thing to do, is try your best to get a direct flight. Bring your bass guitar to the airport in an ATA approved flight case. Then walk it all the way to the airplane. That way you will be with it at all times, at any possible security checkpoint. Be as nice and polite as you can be to airport personnel that may question you about what you have in the case, those who want to inspect the case and to the ones who can assist you. It is important that you are nice and polite and smile, even to airport security people who might not be nice and polite to you. Anyone can have a bad day and some travelers before you could have been a headache to the security person. Nicely ask airport personnel if they can do anything to help you and that it would be greatly appreciated. Tell them your instrument is a your baby, like a sweet car is to an automobile enthusiast. You can also tell them that your bass is your livelihood (whether it is or is not) and that you cannot afford to have it become missing or damaged. Tell them you would like to handle your bass all the way to the plane if possible. The person at the gate will arrange to have someone meet you just as you board the plane to take your guitar and they will put it in with the baggage. By that point you can lock the case. Make sure you see the I.D. badge of the person who takes your bass from you. It should be plainly visible. If his or her I.D. badge is not visible, ask them to please show it to you. That person will give you a special claim ticket for when you get off the airplane. The scenario that I've just described will only work out well if you have to change airplanes during your trip. If you have to change planes to get to your destination, you will have to check your bass just like you would check your luggage.
Sometimes you get lucky and they will let you take a guitar on the plane. I wouldn't take such a chance with a gig bag. If you were very lucky enough to have been able to bring your bass on board on one flight, it doesn't mean you will be as lucky on your return trip, even it is the same airline. Very important...do not make a joke about having something dangerous in the case. Especially in this day and age, the security people will not appreciate it, nor your fellow travelers and you might find yourself in trouble or at least very delayed for making such a statement.
An alternative, would be to ship your bass ahead to someone you trust very much and have them ship it back to you when you return home.