Paintball Advise #3

Finally, I got a good gun. A Tippmann Custom Pro. Works very well, but they say it's a "beginners" gun, maybe, not the point. What is though is this:

Can ya'll give some advice and info on what I can and should upgrade it with plz? I don't want to spend more money on another gun I don't need.

Also, I fired it yesterday, but[this might b stupid] when I took the Co2 bottle off, and tried to screw it back on, it keep spraying. Plz answer soon, me and my dad r going 2 try and "fix" it. Let me guess, it needed to stay till it was empty, right?

[edit on 16-7-2005 by SEAL Trident]