Doula, Childbirth Educator and Doula Trainer Janice Banther has created a series of videos she calls "Doula Mentor" videos. They are extremely informative and helpful videos, especially for new doulas!
You can view all of her videos on her YouTube channel:
Doulas and Phone Calls
Doulas: What to Wear?
Doulas and Elevator Talk
Doula: What Helps During Hard Economic Times
Doulas and Scheduling Births
Doula: Have you Read?
Doula: Helping a Client with a Panic Attack
Doulas: Working With Sexually Abused Moms
As with any advice, you have to decide what will work for you and what you don't identify with. But its always nice to have a mentor!