I think the important thing is to go with what you are comfortable with, even if it means at first you walk your bike through sections you are unsure about. I also find that not looking at where I don't want to go on my bike helps. I think it helps too to put your weight back and not use too much front brake in the rutted downhills ("feather" the brakes). The narrow singletrack takes time to get used to, but trust that it will get better with time. You have to find that balance of going fast enough (to get through the terrain) and not too fast for your comfort, which takes time like anything else.

I also like to use visualization techniques (there's some books on the subject that explain it better than me...one is Sports Psychology for Cyclists).

I have never been to a mtn. bike camp for women, but I have been to a road biking camp which did wonders for my bike skills on the road. I am sure this would be fun for you to experience something like that with mtn. biking. It helps to ride with other women...you see them doing things and you're like, "hey, I can do that!" So, maybe you could find a group of like-minded gals to ride with in the sections you are worried about. I am sure you will be just fine!

You go girl!

Sincerely,

Lisa