It's all in the thread
Start by doing what NATS tells you, study the motivational paper. You might also want to revise some Speed/Distance/time calculations.
In the end the most important in my opinion is how ever to get a good nights sleep, a proper breakfast and then do your best. These tests are a lot about aptitude (the first two papers of stage 1 and part of stage 3 excempted) so it's not that much you can do to prepare.
Good luck
On a side note, have nobody from stage 3 on the 31st heard anything yet? Oh well, "no news is good news" I suppose
