This feeling right here is why I spend at least half of my prep-time doing mocks, rather than trying to memorize my cheat-sheet. The sheet is going to be there for you, but once the adrenaline and the nerves kick in it's easy to make some silly mistakes.
If you've got time, run through a quick mock draft that has the same league settings as your league. It'll take the edge off the first handful of rounds and you'll feel more comfortable with it. Besides, about 90% of the time the managers in your real league won't be as knowledgeable as the guys you're doing the mock with.
Once you've got the core slots of your team filled in comfortably you can spend the rest of the draft filling holes in your roster, looking for value that's dropped too far, and snatching up prospects that nobody else will think of.... instead of spending the second half of the draft worrying about the mistakes you made in the first half of it.