For women, use the center of the bra, facing the body in that small "chamber"...may or may not work. For men use Tape (there's a special kind) to atach the mic to the body or protect it from cloth friction. Get a Boom!! nothing like a nice shotgun condensor well aimed. Also, if the actors are still, you can hide lavs close enough to capture dialog. Experiment, get a reliable wireless system (lectrosonics cames to mind)...Good Luck!