Please note: I do not own and have not paid for anything listed below. They were either made by me or can be found open access on the internet.
Practicing using past exam questions on the official College Board website.
Always remember to time and score yourself.
Note down your mistakes - this will make it easier for you to target weaknesses.
Do targeted practice using Khan Academy's free resources.
A few days before the test, take the official Bluebook practice tests to familiarize yourself with the testing format.