First and foremost, safety. The fun will pretty much take care of itself, being safe though is your personal responsibility
. Listen to staff, apply what you hear.
The first time you get hit, resist the urge to lift your mask. I know it sounds ridiculous, and I have no idea why people do it, but it happens. If you don't do it, I can pretty much guarantee you will see someone who does.
From a clothing standpoint, wear comfortable clothes that give you full range of motion, and can take a beating. Bring a hat, wear it backwards, put your mask on over it. Rental masks are sometimes tough to get fitting tightly, and often like to slide down the back of your noggin. The bill of that backwards hat will keep your strap, and your most important piece of protective gear right where it belongs. Do you have a set of cleats? Wear them.
Have a couple of old towels or rags in your bag. They will come in handy one way or another. If you like to keep your vehicle clean, bring extra clothes for the ride home. Don't be embarrassed, you are FAR from the first person to change in the field's parking lot. Water and food have been covered. Even in pleasant weather you will get dehydrated, bring some high quality H-2-O.
Playing. Gun up, body facing down field. You can't shoot anyone with your gun pointing down, and your back to your bunker. Using a rental gun? Double tap. If you don't hit someone with the first couple balls, you're probably not going to hit them. Pull twice, gauge the results, pull twice more. Having trouble hitting a guy? Move closer. Long ball eliminations are fun, but REALLY impractical. If your shots can barely reach the target, move closer. Don't worry about the bad guy being able to shoot you if you move closer, he's usually too worried about YOU shooting HIM to do anything about it.
Try stuff, especially early in the day. Go out there, and go right at it in game one. The worst thing that happens is that you get hit and have to wait for game 2. You can't really embarrass yourself because you're new, and to be honest, people are expecting you to make a bonehead mistake or two. The more stuff you try, the quicker you'll begin to figure out what does and doesn't work. As an added bonus, "regular" players are more likely to reach out to a guy they see actually participating in the game and trying to learn.
You're panicking, don't panic.
That move you're thinking of trying? You could've done it by now...and now...and now. Nothing is more frustrating than watching a player stick his head out of his bunker for 30 seconds trying to decide whether or not to make a move that will take 2 seconds. That guy who you think is looking right at you? He probably isn't looking. Fire a couple balls at him, and go. Not all moves have to be big moves. In fact a couple of small, easy moves, can easily add up to one big, difficult move.
Off the field, make friends. Paintball players pretty much all love talking about paintball. Ask questions, engage other guys off the field. Be polite. Yes, you can touch/hold my marker if you'd like, yes you need to ask first. Don't know what kind of gun/hopper/barrel/whatever that is? Don't guess, just ask. For the love of God, don't ask what it cost.
Wondering how good a player is? Here's a handy guide for you...
That should get you well on your way to having a good first day out.
Welcome to the game, and enjoy your time here!