Go to a game, learn the game, get a feel for your gun, go from there. Do upgrades in jumps. FPS low but not very accurate? Get a tightbore or a new bucking. Next game, see what that does for you. You play the next game, accuracy up, but still low fps? Get a new spring. That way not only do you learn about upgrading/maintenancing in steps but you also know what you need to get instead of just jumping in and buying a bunch of random parts. For all you know, just a bucking and a new barrel would bump up your fps to 400. Pretty unlikely, but if you had bought a spring with that, you now have a spring that you don't need. Also, don't be afraid to ask questions because most of the people (at least in real life) will be totally willing to help you out. Just because some of the guys might be a little bitter doesn't mean we all are
Oh and make sure you do some research and if possible get someone else to work on your gearbox before you break it open. Last thing you want is a dangerous looking paper weight.
And just a word of caution, a lot of people will ride you hard pretty much for being young. In Airsoft maturity is a highly valued thing and for a good reason. As long as you don't act like an idiot and don't make stupid choices you should be fine.
