Bacterial growth is what causes the odor. Wash daily with a good soap, like Dial. Pat dry and apply anti-perspirant deodorant. I've heard that dabbing with white vinegar helps, which makes sense. It's mildly acidic so would kill any residual bacteria and it's a natural deodorizer. The smell dissipates quickly so you're not going to smell like vinegar. Last suggestion is to try using deodorant made for men. I'm female but use brands like Right Guard because I think they work better than the frou-frou stuff made for women. Just stick with the "fresh" or "clean" scents and no one will know you're using it.
Use the degree girl. the dance party one is good for smelly pits, but I could not use it, it gave me really bad headaches. my sister loves it though. and she needs it!!! because her pits stink!!! she is only 8, but her pits STINK!!!!