Depending on the turn, I typically use both brakes. The more experienced you get the more you will use the front brake (once you figure out how far you can push it before the front end washes out on you). Braking bumps just before the turn tend to hinder the use of the front brake depending on how big they are. Also, the type and power of the bike will determine what gear you need to be in around the turn, but 95% of the time 2nd gear is a good choice (unless it is a large radius turn, then maybe third). I never use 1st around a turn. On small bore bikes (125 cc and less) just feather the clutch around the turn to keep it from bogging (keep it in the powerband).
Good luck and have fun! Practice those turns a lot, b/c that is where it pays to be fast. Some other helpful tips are to keep your elbows up, weight the outside peg, get your inside foot out front to use as a counter-balance and to dab the ground if you get leaned over too far. Also, don't look down at your front wheel, but keep your head up and look where you want the bike to go.