Birdy, I was reluctant to do my first one, too -- so many years ago!
Relax. Do the first one, and if you get too nervous half way through, excuse yourself to the employees, go home, and reschedule it. You can then evaluate what was making you nervous, and do whatever it takes to get over that.
For every different station I do, I have a one-page cheat sheet; it lists the required photos and the things I'm really bad at remembering. And I'm one of those clutzes that sits there after the shop is completed and go over the questionnaire just to make sure I didn't miss anything. Now I've done hundreds. I do whole routes of nothing but gas stations (with maybe a fast food in there somewhere!).