What is your budget?
I agree with the good mask (JT or profilers). Find out what your style of paintball is: electro, mech or pump. I would seriously give pump a try, for field entry and a bag a paint (roughly $33 together), I can play all day and hang out with friends. My S6 sold me on pump play.
If you are on a budget, pick up a used A5 (Tippman) and run C02 until you can afford HPA (carbon fiber tank/reg...high pressure air). The barrel would be your next upgrade. With the A5, you can run a "cap" unstead of a hopper if you are looking for more of a milsim look.
Paintball is a blast, go out a play it before you start buying gear. Mask, buy it new...marker...used in good condition from someone with good feedback.
Originally posted by heinous: "sniper's gun always gets extra camera love"