This might spoil it for some people - but take several pictures of this person with different facial expressions. Based on the "un-biased" decisions of the editor/paper-owner/article writer, they might want to use different kinds (One that makes them look mean, proud, dumb, funny, important, etc.)
Also try to get a horizontal and vertical of each shot (your editors will love you). Oh, and if you're going to be in the "pit" at the front of a stage, you'll be on your knees/ass for a long time - pop a few Excedrin/Aspirin or whatever an hour before your shoot and you'll be golden.
Yea, definitely prepare ahead of time - make triple sure you have everything and TEST FIRE YOUR CAMERA before you leave for the shoot. I can't tell you how many times I've taken a shot 5 minutes before I leave, and realize I didn't have a card in, or there was a huge smudge on the lens I was going to use, or my sensor was dirty.
Also, watch the pro's you'll be surrounded by. Theres nothing wrong with learning by copying somebody with more skills that you! If they move someplace to get a different angle, try it! Sometimes you might feel in the way, or awkward if you move, and each event is different. I usually just get a feel for what everybody else is doing and follow suit.
Good luck out there!