I've only done the advanced compass test, but the only advice i'd give you is simple: don't worry about it. It's all very easy and straightforward - They are not looking for supermen! They just want a fairly balanced and rounded individual.
The maths is pretty simple: you get a formula, you work it out however you want to (yes you can use paper) and you write in the answer. Some are multiple choice, others are open. You're unlikely to finish the test because you will run out of time. It's all very, very basic, early high school level.
Really don't worry about it. You'll only stress yourself out. Don't bother preparing, you don't need it. Don't spend money to prepare. Honestly!