My suggestions are very basic-but time consuming:
1) work on your already stated personal issue with fear.
2)read, study, learn and meet other poly's in the real world.
DO NOT TRY HAVING A POLY RELATIONSHIP.
Just do the first two. They will help you with personal growth more than any relationship AND you will be in a better position to decide what is or isn't a healthy relationship for yourself after.
"Love As Thou Wilt"