Definately start with fingers. That will loosen it up a little bit, and you have to get her to relax also.

I would disagree. Just one knuckle deep is going to feel a lot different than all the way in. At that depth, the finger will be pressing against the outer sphincter, which can be quite unpleasant. Once it's all the way in, the unpleasant feeling disappears.

slow - lots of lube and start with fingers - you don't want to make it so bad she won't want to try it again - sometimes women tried it and it was so awful they didn't want try again - when they do w/ someone that does it right they enjoy and can become a great change up sexually

Definitely use good, non-toxic lube. Suggest she "go #2" sometime before you try it. This is a sexual act that should be discussed.

This isn't a time to go "whoops, it just slipped in."

Another word: patience. Remember, unless you had an instinct for sex, you were not very good at sex nor going down on her/him the first time.

Start slowly. One finger the first session...and slowly progress. This is just like dating as a kid - you have to get to each base, a slow progression, before "scoring."