Psychotherapist Mary Pipher, to use her terminology, is no ''woo-woo practitioner.'' Her methods are down-to-earth and described in a refreshingly straightforward manner. ''For me, the best trick is not to have tricks,'' Pipher counsels in her introduction to the latest collection of missives from Basic's mentoring series. Unfortunately, the author of 1994's Reviving Ophelia occasionally resorts to simplistic mnemonic devices (''this ABC triangle of affect, behavior, and cognition'') and florid prose (''I enjoy the earth in all her costumes''). But if, at times, Pipher sounds more like a mother or friend than a Ph.D. (''get more rest, do good work, take things a day at a time, and find some people to love''), that's just her unpretentious charm.