Probably the first step is to go along to a tourney to watch, gives you a good idea of what's expected & what the standard is like. Secondly, try to find some nice team or player who will come along & give you a hand training. Ideally, you want to find an experienced player who needs a new team to play for & try to persuade him/her to join your team, at least for a little while.
You will need to practice working together as a team, preferably on the kind of fields that your local tourneys use - no use practicing on sp'air if it's all wood locally or vice versa. Work on communication especially. Then look at techniques such as snap shooting & sweetspotting.
Keep watching other teams at tourneys, you can learn an awful lot just by seeing others get it right or wrong. Hanging out with teams at events also gives you a better idea if you have all the kit you're likely to need to play at this level as well. Paintballers are nearly all lovely people & will go out of their way to help other ballers, so just ask & usually they'll answer all your questions no matter how naive they may seem.