I believe that it may help if the person believes a past life may be affecting them strongly in this life. I'm a reincarnationist to the core, but I have doubts about the methodology.

I'd be afraid to go to any type of therapist who wanted to hypnotize me. The subconscious mind is a sponge, and you don't know exactly what the therapist is putting out there for your subconscious to suck up & then spew out at an inconvenient moment. Not to say that past-life regressionists or hypnotist therapists are 'out to get' the patients, but you never know what they might say or do that your subconscious mind is going to latch on to like a pit bull...