There's a ton of great advice here, but let me add some here.
Its normal to be nervous. We all were the first time. But don't be too self-concsious about it.
!) The most important thing is communication, and not all of it will be verbal. Pay attention her reactions. It will tell you a lot about her desires. If you aren't sure, or are getting frustrated not knowing talk to her. Women tend to get off on talk more than we do so don't feel wierd about tell her how hot she is. This is especially true of a woman who isn't model thin with gigantic breasts. In other words, almost all women. Talk to her even before sex. Don't necessarily tell her all your worries, she should already know that you are new to this and are understandably worried. Rather tell her that you want to please HER. You want to feel and hear her orgasms as much as you want yours.
2) take it slow, a lot slower than your natural drive will enourage you to go. As a man, you will be driven to go FAST. Women go slow. So if you want this to be a good experience for her, go SLOW!!!!! If she wants you to go faster, she'll likely tell you.
3) Think about this from her point of view. You most likely are bigger than she is, and almost certainly stronger than she is. That can be very intimidating for a woman. Then add in the fact that you plan on thrusting a part of your body into her, while she is in a very vulnerable position. If you have a larger than average penis that only adds to this, though frankly even a relatively small penis could seem intimidating to an inexperienced woman. You will need to reassure her. Tell her that if she is feeling any pain to let you know. Remind her that if she wants to stop you will. But also remind her that the further along into the sexual encounter the two of you go the harder it will be for you to stop, and if you have to you may seem angry. She needs to understand that anger is your sexual frustration that every man feels under those circumstances. It is instinctual.
4) Use a condom, there are NO excuses not to (except maybe for an allergy).
5) As for oral sex. Don't worry too much about it. Once you find her clit, you are about 70% of the way there. Every women is a little different in how she likes it, so remember my first point, communication!!! Pay attention and it should be evident. If it isn't just ask!!! (Assuming your tounge isn't too worn out already LOL)