Think of every day as something new and shrug off the previous day. It is a learning experience. As a new grad myself, some shifts go well, others are a challenge (but my favourite because I love the rush!), and some... well just don't overthink them. My biggest flaw as a nurse IMO is going home and overthinking what I could have done, what I should have known, or what I forgot to ask. Keep a mini-pad on you for questions, and do write them down. I swear I tell myself I'll remember at the end of my shift, but I can tell you I remember about 10% of the time:).
I know it has beeen mentioned on the blogs a lot lately, but a journal will be your best friend. I love writing down things to research, or signing up for classes in the area (most of them are offered free through other health service representatives if you check the paper or online).
And always remember to have a day to yourself, relax and enjoy:)
In the end, a little nervous is a good thing:) From your post, I know you'll be the best nurse that you can because you're willing to learn, and you're excited! Best wishes with your orientation!:)