Welcome Draco, main thing is try a few sites if you can, run with hire AEGs to start with, and get a feel for different weapons and loadouts . There are many different games from basic "capture the flag" to full on 24+ hour milsim games and everything in between; playing an online game is totally different to airsoft as Samurai said, for example generally if you get hit once you are out and need to respawn, though some games will allow medic rules, and as a newbie you will get shot a lot more times than you hit someone else, mainly because more experienced players will know the site better than you and they may well have much better set up guns. If you take the time to learn from others you will see the benefits in your own abilities. Sniping in airsoft is a whole skillset in itself, yes you can use a bolt action rifle by all means if its your thing but if you're attacking you will be at a disadvantage compared to an AEG until you have learned the stalking skills required to get the best from a sniper role, and also if it fires above 350FPS in most cases you will have a MED (Minimum Engagement Distance), generally around 30m, so you can't engage anyone nearer to you than that.
I suggest you just get some airsoft skirmishes under your belt, talk to more experienced players and learn how to play effectively, don't get disheartened if you get shot a lot, learn from it and you will quickly improve. Above all have FUN doing it!