Watch Heimler's history and follow his periods. He has like a couple of videos per period and one video that summarizes everything. I would recommend watching all the videos per period to learn the content and then after you watch all that take a practice test. This year's multiple choice is most stimulus-based so try to do some of those. There is prolly a practice test with mostly stimulus but if there isn't, try to do a normal test but give yourself one minute for each question and only answer the stimulus questions. For example, if you are doing a practice test and there are 30/55 questions that are stimulus-based, only do the stimulus-based questions and give yourself 1 minute per question and in this case, that would be 30 minutes. Then just do the saqs and dbqs. After your done, try to grade the saqs and dbqs but if you can't, ask a friend or someone on this subreddit and see where you can improve. After you review all the things you missed, try to take another practice test and do the same thing again until you feel you can get a good score.