Having passed all three stages and been given my start date for the college I completely agree with the previous two statements. The best thing to do is relax, sleep well, and eat well the day of the testing.
The most studying I did when I was going in for my testing was read the information NATS sent me(several times) and took down some notes on the main things and abbreviations.
Aside from that I got a good nights sleep, a huge breakfast, and went in with a positive attitude.