Congratulations on the job! You are going to do great! However, it can be anxiety provoking to face your first day...so know that feeling nervous is a normal response.
Take notes if the circumstances allow. This is the best way to assure you remeber everything. If that's not possible...try repeating things that are told to you. This is a good trick to make details stick in your mind. (you can repeat things out loud, or silently to yourself.
Making word associations with pictures in your head helps too. Anything that helps you recalls details...rhymes, songs, acronyms, ect...these are all games I have played trying to remember things.
You are going to do a wonderful job! They hired you for a reason...have confidence in yourself!
Let us know how it goes, okay?