The ACT covers a larger array of concepts than the SAT, therefore finding the right books to help you prepare is essential in achieving a satisfactory score. The Official ACT Prep Guide provides questions that are very close to the ones in the actual test, which is necessary because the format of the test is not like the tests you are used to taking regularly in school. This book is the best source because it gives official questions contained in previous tests. This is better than the questions provided by other editions.
The ACT English sections cover grammar extensively, therefore The Complete Guide to ACT English by Erica Meltzer will really help you on the ACT material. Meltzer’s The Complete Guide to ACT Reading is also great at teaching strategies to tackle logical reasoning problems the ACT extensively covers. The Ultimate Guide to the Math ACT by Richard Corn can help improve your core math skills in an organized manner so that you can really improve on areas of weakness and have an overall better score.