Baby powder! Before and after. Use it liberally. Seriously, it helps. The medicated stuff is great (gold bond, Dr. Schols), but baby powder is 1/2 price and works pretty much the same. Also, use a good fragrance free deodorant.

Personally, I try to avoid fragrances. You don't want to smell, you just don't want to BE smelled. Anti-persperant (absorption) is the first step. Feet. Pits. Cr0tch. Anywhere else you sweat. Really, try it.