I want to upgrade my gun, what is the best way to do that?

Gun upgrades can be done in a number of different ways depending on what you desire your gun to do and what type of gun you have.
I have a spring gun...
Most spring guns don’t have any upgrades available mostly due to it's low quality.
I have a gas gun...
Metal slides and frame are popular for gas pistols and are the best way to increase the looks and durability of your pistol. High flow valves and stiffer springs are another great way to achieve more realism and power. There are also many other blowback upgrades to increase durability in order to user higher power gas.
I have an AEG...
There are numerous upgrades available for the various AEG’s on the market. However, there are some low-end airsoft guns that you are unable to upgrade such as UTG, CYMA, Well, etc. Depending on how much you want to spend, you can upgrade the gears, the spring, the piston, piston head, and so on to increase the rate of fire, the reliability, and the velocity of your BB’s for your airsoft AEG. Some guns have limitations on what you can upgrade due to battery capacity, barrel length, and gearbox size. We do offer upgrade services and packages on our Upgrade Service link on our web page.

Source Airsoft GI

Ebola wrote:

Gun upgrades can be done in a number of different ways depending on what you desire your gun to do and what type of gun you have.
I have a spring gun...
Most spring guns don’t have any upgrades available mostly due to it's low quality.
I have a gas gun...
Metal slides and frame are popular for gas pistols and are the best way to increase the looks and durability of your pistol. High flow valves and stiffer springs are another great way to achieve more realism and power. There are also many other blowback upgrades to increase durability in order to user higher power gas.
I have an AEG...
There are numerous upgrades available for the various AEG’s on the market. However, there are some low-end airsoft guns that you are unable to upgrade such as UTG, CYMA, Well, etc. Depending on how much you want to spend, you can upgrade the gears, the spring, the piston, piston head, and so on to increase the rate of fire, the reliability, and the velocity of your BB’s for your airsoft AEG. Some guns have limitations on what you can upgrade due to battery capacity, barrel length, and gearbox size. We do offer upgrade services and packages on our Upgrade Service link on our web page.

Source Airsoft GI

Upgrading your AEG depends on what AEG you have. if you have a sportline or beginners weapon, you may just want to bump up the FPS and possibly get a few internal parts like a FM spring guide, a new piston head, Polycarb pistons, even shim you gears too. but most sportlines dont last so putting too much into it may cost you later. if you have a professional grade weapon, like G&Gs Top Tech, odds are its already pretty well made so tuning it is probably the only thing you need to do, like getting a fast motor for a Lipo. no one can tell you exactly what you need because every gun is different and every gun needs to be tuned in different ways.

Gas guns dont really need anything unless its a GBBR or like an MP7/MP9. pistols, from what ive seen, may only need an FPS reducer, but as far as externals, bling is the only upgrade i can think of. if you have a TM, you may need a second job lol.

Springers, except snipers, you cant really do anything cause they are usually cheap enough that if it breaks buying a new one wont bankrupt you.