The SAT has 96 Reading and Writing questions, while the ACT has 115 of these questions. This higher number means that you have more opportunities to do well in your areas of strength on the ACT Exam. Furthermore, the SAT has two Math sections, while the ACT exam has one: if you'd prefer to take a "one (section) and done" approach to math, then the ACT could be a better fit for you. 

2. In the Reading section, answer the questions out of order. 

Since you'll answer a combination of specific questions and "big picture"/"global" questions about an entire passage, it's important to answer the specific questions first, and then the "global" questions last. You can consider re-ordering the questions in your own P.O.D. (personal order of difficulty): answer all line reference and paragraph reference questions first ("In line 5...." "The fifth paragraph...."). Then, answer key word questions: these are questions without a line reference or paragraph reference, but they don't ask a general question about the whole passage. These key word questions contain key words that you can find only in the passage. After answering these two types of questions, you'll have enough knowledge of the passage to answer the global questions to ask about the whole text. 

Although many ACT English questions focus on grammar, there are also questions that address sentences and the entire passage in front of you. This is why it's essential to pay attention to both the details (grammar) and the "big picture" (the entire text). 

Although this last portion of the ACT exam is optional, it is better to complete the essay and not need it than to skip the essay and need it. Thus, completing the essay at least once (so you have it available to you) is worth considering. 

 When starting to prepare for the ACTs, students commonly leave questions blank when they're stuck. However, your ACT score is based only on the questions you get correct: in other words, there is no penalty for incorrect answers. That's why it's better to guess for a tough question, since you can still increase your score, than to leave it blank, which would guarantee that you won't gain any points from that specific question.

There are many ways to approach your ACT preparation, and your style is up to you. However, remembering the five tips above can help you maximize the energy you devote to your preparation!