Just as what Walker recommended, stick to the OG and really understand your errors. If you're looking to score over 600, OG will do the trick provided you understand the question/answer (If you're aiming for over 700+, you'd probably need some more time/resource).
The day prior to your test, just relax - watch a movie, etc. Get a good night sleep (though most ppl would be just too anxious for the test to get a 'good' night sleep) and eat a good breakfast. Don't do anything out of the ordinary that you wouldn't do on a Sunday/Monday. You can briefly review some of your errors on Monday, but I wouldn't focus much too much on any particular topic.
Last, but not least, take the test like there's no tomorrow and pay attention to everything.
Get the best GMAT Prep Resources with GMAT Club Premium Membership