Cunnilingus....how many techniques are there?

I've given head to a girl about seven times, before I tried the first time, I did what I thought was a smart move. I asked her to show me what to do. Ladies, what are some good techniques that you would suggest for the not-so-learned fellas that want to please the ladies they are with orally? While explaining, please and I mean please stress the do's as well as the don'ts.
Thanks..