There is nothing to study! If the tests are administered properly they are trying to assess your personality.
Not quite true - they give you the advanced compass test, which amongst other things tests mental arythmatic, memory recall & coordination aptitude...
There are some test online here which replicate certain sections (apparently harder than the actual compass test) I'm not sure how closely these represent the actual tests... Perhaps someone who has sat them might offer some input?
Unless of course you actually mean just the psychometric test (as opposed to the Advanced Compass test), of which both are covered in the day.