Find a good preparation book at your local or online bookstore; look for one that includes practice tests.
Dig out your old class notes on the relevant subjects.
Work through your individual subjects in detail. Your prep book should have tips and practice tests specific to each subject.
Study a little bit each day, making it a part of your daily routine. Start studying early so that you recognize your potential weak spots. Buttress these weak spots to increase your confidence and minimize your anxiety.
Take as many practice tests as time and patience will allow. Simulate exam conditions as best you can; for instance, make sure you have a 1-hour chunk of time - for each test - when no one will bother you.
Learn as much as you can about how the test is organized and structured. For instance, if you can eliminate one or more answers as incorrect, you're better off guessing among the remaining answers than leaving the question blank.
Familiarize yourself thoroughly with the test instructions. This will save you time when you actually take the test.
Talk to people who've taken the test. Those who have been through the fire often have the best advice.