Chemistry can be hard when it seems like every new problem is different from the one before it. The AP course and test are designed to make sure you understand how chemistry works so that you can select the best equation to find a solution to a problem and then can rearrange the equation to get your answer. This might be a different way of looking at chemistry than you are used to. It can help (a lot) to be able to see more worked examples of types of problems than you might see in a lecture. You might want to supplement your lecture and textbook with a study guide.
My favorite study guides for AP chemistry are The Princeton Review: Cracking the AP Chemistry Exam and CliffsAP AP Chemistry, which comes from the people who brought you Cliff Notes. In both cases, the subject matter is presented very clearly, with summaries to highlight key points, many worked problems, and 2 full-length practice tests. If your school library doesn't have a copy of either of these books, most public libraries keep them. Earlier editions are good for providing examples, but since the AP exam can change from year to year, you'll get the most benefit from this year's book. The study guides are good for more than just AP class, though. They are excellent supplements for a college general chemistry course or actually are a good way to teach yourself the principles of chemistry if you are studying it on your own.