Dr. Milton Erickson is the renowned father of modern hypnosis. Read his books carefully, they are amazing. An especially good introduction is "My Voice Will Go With You", which is a collection of Erickson's stories, written by his student Dr. Syndey Rosen
Hi
Erikson's work is amazing, but IMO a little difficult to for someone just starting out.
Trancework by Michael Yapko is very good & comprehensive book to start with.
Trance-formations by Bandler and Grinder will also get you up and running very quickly with useful language patterns.