I would steer clear of fiber supplements and high fiber foods as they definately cause gas. Try and keep yourself as regular as possible, having bm's everyday. Constipation will cause more gas.
Probiotics will help minimize gas but you may experience a temporary increase when you first start taking them. In addition, with C they can sometimes slow down the system too much and cause even more trouble.
For me, the best way to keep gas at bay is to avoid getting constipated. If that means taking a laxative once a week just to "clean out", then that's what I do. I don't ever have a problem with gas "accidentally" slipping out. I struggle with the "trapped" gas that usually requires effort to break up and pass.