Re: I can't seem to keep my clothes on!
My experience is similar to Don's with the belt, but I can recall only few times where the pants have come loose.
As a previous poster has mentioned - pull the drawstrings out sideways until the pants are TIGHT. Put the drawstring through one of loops in front to keep them from riding around. In judo I tied the know with the loop inside the bow, in aikido the knot is off to the side - I don't notice a difference. Tie a bow - make sure the strings are drawn tight enough so that at the end of practice it takes a while for the skin to recover its "strapless" look...
The hakama helps with keeping the belt on, but whenever I'm doing anything without the hakama, any belt I've ever worn - old, new, judo, aikido - works loose.