Definately the Pre-ACT. I got a perfect score on the ACT and i realized that doing practice ACT tests have really helped me. Start of by not timing yourself. This way, you can know if you really know the material or not. Once you do a few like this and meet with someone (tutor or brainly) to discuss and learn from your mistakes, you can start to time yourself for the next few. I know this can be a lengthy process but bare with me because the results will show! I know you are a very smart and capable student and never give up hope. This is key!! Also, what grade are you in because I can give you a study plan you can go by depending on how much time you have!!