OAKLAND, CA Tae kwon do instructor Darryl Connally, 42, said Monday that he never teaches his students everything he knows about self-defense. 'I give them enough to get by in most street-level confrontations,' said the author of The Nearly Complete Guide To Urban Security. 'But you never give a potential opponent an edge.' Connally added that 'a true master must always be on his guard, lest one of his Basic Women's Self-Defense Seminar pupils rises against him.' 