Unless you're really cramming and it's unavoidable at this point, I would say relax. Don't look at anything. I think it's safe to say that by the day before, you sure as hell need a break from studying 🙂, and it's likely that you won't retain that much more in anyway (unless you're cramming, like I said). If you've balanced out the studying, take the break. It will clear your head and prepare you for the next day.
That being said, I remember when I took the SAT I had a tutor for the english section and I was told to do just what I said (nothing the day before), but to do just a few, maybe 3-5, practice problems the morning of the test. If your test is later on, I guess just wait until a few hours before it starts, but the point is to get you in the right mindset of figuring out those problems without actually putting any stress on you yet. I thought it was a good method.