This isn’t true at all. Every single paintball barrel is smoothbore, with the exception of the Flatline which imparts some backward spin and lift to (in theory and, sometimes, in practice) extend the range of your shot. No serious paintballer uses the Flatline system, and anybody who uses the word ‘sniper’ on the field doesn’t know what they’re talking about.
Similarly, there isn’t a whole lot of difference between a paintball shot out of a thousand dollar marker, and one shot out of your hundred dollar tippmann. Contrary to some suggestions in this thread, people actually don’t “tweak their velocity”. Commercial fields chronograph all markers to the same speed, usually something around 270-280FPS for outdoor play. Not only is it readily apparent when somebody’s blasting you with hot velocity, but it’s a major no-no that’s going to get you kicked out really quickly. The real difference between equipment is rate of fire - modern electronic markers shoot really fast, but everybody’s rounds travel the same distance at the same speed and mostly the same accuracy.
Eyeglasses under masks can be a bitch - yes, spit and anti-fog sprays can help to some degree, as can duel-layer thermal goggles (unlikely since you’re renting.) I generally am forced to take my glasses off, but my prescription is fairly minor. It’s doable, but highly inconvenient. Since you’re renting, chances are you’ll fog up extremely quickly, particularly if you’re panting and perspiring a lot.
Getting shot is no big deal. Paintballs will leave doughnut-shaped bruises just about anywhere, and their fragments can inflict some superficial cuts if you get shot on exposed skin. Besides the crotch, catching it in the hands is probably the worst. Getting shot in the throat sending you the hospital? Not so much. Paintball is one of the safest sports, below golf and bowling in terms of injury rates.
In terms of tactics the best thing you can do is be aggressive. I’m assuming you’ll be playing with lots of other newbies; many of them are going to be extremely intimidated by the sound of paintballs smacking their plywood bunker. New players spend a lot of time hiding behind cover instead of looking around, advancing up one side of the field gives you a lot of fun angles. I should mention that getting shot in the back when you’re not expecting it really sucks. But it’s so satisfying doing it to somebody else.
My general suggestion is to not worry overmuch about what people are saying (somewhat dramatically) in this thread. Get some pants and a long-sleeved shirt you don’t mind ruining, go out and have fun. Since you’re at a commercial field, you’re going to get safety lectures like the ones in here over and over. Fields are well aware of the liability involved with paintball and tend to be extremely careful about safety and barrel covers (plugs? man, when did you guys last play?). Just relax and have fun, paintball is a singularly unique experience. Kind of like computer games in real life except you can still respawn.
On preview this might come across like I’m calling out Oakminster and co. This isn’t true! They’ve given you excellent advice, I just want to clarify some of the things they’ve mentioned. Paintball is a much smaller deal than most people think it is. Go have fun!