I'm happy for you. I don't think you will be awful at all. I hate that people say you will be awful the first time, I think awful should be reserved for people that literally ignore all the rules and do way more negative things than positive things. Recognize that it is practice and you are basically gathering information.

I think something that might help is to break everything down logically; there are some universally acknowledged good and bad things, and then there are things that are unknowns and you can't really be faulted for which you should not feel bad for because they require practice, are dependent on the individual, and which you will absolutely improve on.

So maybe what you can do, is make a list of things you know are good and what you know are bad for each thing you might plan to do, and a list of all the things about the acts that you aren't sure of (because those are dependent on the individual, require practice, and maybe experience) take that list and identify which parts are things that are general knowledge and things which require practice or knowledge you don't have access to.

If I might give an example; you probably intend to stimulate her with your hands the first time. The pretty much universal good things to know are that clitoral stimulation is very important, and that it's also very very sensitive. The universal bad things would be putting way too much pressure or going too fast and rough. The things you don't know exactly are how much pressure is suitably 'gentle', what paces, and what rhythm or patterns. Keeping in mind the things you don't know, you won't get all down on yourself when you go to rub her clit and it turns out she wants a little more pressure on it (you were gentle because you knew too gentle was much much better than too rough!). She'll be happy you are stimulating her clit, and she'll be happy that you were gentle.

Do all the good things, don't do the bad things, and no one can accuse you of being awful! Compare that to the stories you hear of guys being way too rough, giving no clitoral stimulation, rushing into it, etc. You cannot POSSIBLY be considered awful in light of all the actual things that people do to make sex bad rather than at least pleasurable and worth pursuing further! Hope this gives you more confidence that you will do good if you know what good is!