Eh, the main thing is not to stress over it. The night before the SAT, you've done almost all you can do. The only thing you can do is remain calm, do a fun/enjoyable activity that won't rile you up and get a good nights sleep (at least 8, but preferably 10-12 if possible).
Try to have a normal, not too stressful Friday (hey, you'll have school, unless you have a religious exception & take it on a Sunday) In my experience, if you review on the night before the test, you get way too anxious. My personal suggestion is to set out ALL of your test supplies (wallet w/ photo ID, sharpened pencils, I bring a separate eraser, calculator + change of batteries, a snack), eat a favorite meal (possibly a desert too), do a fun but easy activity (TV springs to mind), and get to bed early with nothing on your mind.
When you wake up on the "big day", eat a big breakfast (I get a little nauseous before the test due to this, but it's 45 minutes of getting ready + driving before I get to the test center so I'm not by the time I get there, and I'm very awake and alert, not distracted by hunger pangs). I try not to think about the test itself until I get into the test center.
For tips once you start the test (and get fatigued towards the end) see "How to stay attentive for 3 hrs 45 mins.."