Full face protection is a good idea, but a paintball mask is sketchy because of the sighting issues. Do NOT use mesh goggles, bb shards go through the mesh and will hit you. They are not eye protection. Most people use a handkerchief or something similar, Cabela's and the like have hunting hoods that I think would probably serve the purpose best. They're a bit heavier cloth than most bandanas, and they cover your whole head, as well as hanging loose in front of your face, so they'll slow the bb before it hits you.
I wear a thin balaclava, and only got a small red mark on my cheek from a 370fps gun at 20 feet. BB's don't hurt, but you definitely know you got hit if it catches skin or thin cloth. If it hits bone (knuckle, elbow, chin, etc.) it'll sting for a while.