The proper gear is essential-but not necessarily other-worldly. Snipers are successful in plain camo with off-the-shelf markers... they are also effective in handmade ghillie suits with thousand-dollar wonder widgets. It's up to your budget, your style, and the demands of the game. Your marker may be a pump or semi; contrary to popular belief, there is no inherent accuracy difference, so long as you have a good paint to barrel match and consistent volume and pressure of gas released for each shot. With a pump, you'll have to shuck the forearm for each shot, the movement for wich will attract attention. Also, you'll have to work harder to take out a group before they notice your position... but pumps are much lighter, and stock class setups avoid easily-spotted hoppers.
Most of the noice when you shoot is made by the marker, about wich you can do little unless you feel like slipping a housing of 3" ABS plastic over the marker body and padding the internal space with foam. But you can minimize the sound signature of your barrel by selecting one with good porting-most aftermarket barrels are ported, making your choice easier. Just don't charge into the game with a non-ported stock barrel, or you're asking to be compromised.
You'll need paint-one hundred rounds per hour is a high figure, so plan accordingly. The method with wich you feed the paint into your hopper is critical. Players are adept at spotting things like goggles and hoppers in the forest-those shapes don't belong. So, since you need to play in goggles, eliminate the other primary shape by making a good stick feed. 3/4" PVC pipe painted black (or wrapped with electrical tape) is a good start; with a 90 degree elbow, and little sanding on the street nub (between the elbow and the feed port or hopper elbow on your marker), you can make it work with any marker.
Smaller hoppers are also available: from thirty rounds to a hundred. Frequently used by pump players, these smaller hoppers present your opponents with a much smaller target, and are easier to conceal in the woods. A5 owners have discovered the Proteam Products Tac Cap Loader, which replaces their hoppers with a stovepipe-looking tube with a lid on top. The unit comes in three heights: thirty round, forty, and fifty wich you can set based on your paint needs.
As accurate shots are essential, you must have two peices of gear regardless of everything else: a squeegee (not just a swab), and some sort of sight. Paintballs are inherently less accurate then you'd like them to be, but they give you a reference point by wich to calculate for drop and drift. If your paint hits dead-on at twenty yards, and you have a target at thirty, you'll knowjust how high to aim-and be able to aim exactly that height to hit your opponent square in the goggles. Once you train with a sight and learn it's relation to the real world, you'll be amazed you ever played without it. Crosshair scopes are usually overkill, even for sniping. Occulated sights work just fine, and generally don't require batteries... but the most luck players have is with red dot sights. They don't magnify anything- and our ranges are too close to matter-while giving you a bright red dot to aim with, and a wide field of vision to watch your target and everyone else. With unlimited eye relief, they can be mounted anywhere on your marker and used from any angle or distance.
Your camo-and you should wear camo-should fit the terrain. Realtree patterns are great, and military surplus stuff works just fine. Digital vs old-fashioned? It probably won't matter, so long as you make sure the colors are complimentary with the colors on the ground. A ghillie suit is your best bet for extreme concealment, but is beyond the ken of most casual players. There are plenty of ways to hide without one.
Radios are helpful, especially when they're paired with a throat mic and ear buds-you don't want crackling radio traffic to give away your position. Throat mics help you speak more softly, and effectively, without having to move the radio itself.
SNIPERS ARE RATHER UNPOPULAR, ESPECIALLY AMONG THOSE THEY SHOOT... MAKE SURE YOUR TARGET IS WORTH THE TROUBLE