Buy an English literature CLEP study guide book. These guides will lead you through how the test is structured, what the test-makers are looking for in your answers, and many practice questions. It is essential when taking a standardized test to know what the test is aiming for and how it will be structured in order to do your best.
Make flash cards of concepts or authors on index cards. For example, if you are unfamiliar with medieval poems and authors, make a flashcard with "Beowolf" on one side and the central information about the work on the other, such as the era, the style and the main themes.
Use online practice tests. There are many practice tests online to help you get used to the types of questions that will be asked. These online test questions will be different than the ones contained in your printed study guide, expanding your practice.