First, how big's your kit? If it's a 5 piece kit for example, for two mics, I'd have one overhead, one in kick. I suggest you Mic your kick before anything but that's just my opinion.
For three mics, I'd do one smack in between toms pointing as much as possible at the snare drum, one on floor tom and one in the kick. Alot depends on how hard you hit your snare too. If you're a light tapper on the snare, then maybe mic the snare instead of floor tom and move your tom mic to overhead. Snare usually shouldn't need micing as it cuts through just fine naturally. This isn't gospel but just what I would try first to keep it simple.