What can I do to be supportive during my friend's labor?

I bet your local library or bookstore has plenty of books about being a birth coach, which I guess you aren't technically the birth coach, but it should be full of good tips as to what a woman in labor needs. Mostly I guess just ask her during the labor if she wants a cool washcloth, or a back rub, or whatever.

EDIT Also, this might sound crazy, but if I have a good female friend there, I'm also going to want her to fix my hair if it's crazy, or wipe off any mascara that has run all over my face (if the labor was unexpected and I was wearing any) and that kind of thing, bc although I know I won't care how I look at the time, I really don't want to look like holy hell in all the pictures, and I have out of control hair as it is, no telling what sweating and rolling around in bed, and maybe getting in a tub, etc., is going to do to it.

My hubby was my birth coach, and truly the best thing he did was talk to me and keep me interested. It sounds silly, but labor is extremely boring! At least the early parts. So the best thing you can do is talk to her, and let her talk non-stop about her baby. She'll be on such a high. I guess I should mention that I had an epidural, hence the boredom and no need for much physical attention. If she chooses to go drug-free, she'll probably be annoyed by talking! Factor that in when you're with her. Good luck! :)