stick your old "eye of the tiger" cassette in first
start leaping over your mums furniture with all your gear on. and when your dads watching telly go and mug him
on a more serious note
use a mirror its very useful
you can see how much of your body is exposed when you are shooting. and you can work on it.
also for "off hand shooting" just walk around the house with your marker in your off hand and try "pretend" firing with it.
of course their is no substitution for actual practice on the paintball field.
if you are getting into the sport seriosuly. the best advice i can give is watch the pros and AM teams. you will leanr alot
especially watch Nexus as those boys have some sick skillz
J