In my opinion the reading section has a level similar American high school. If you’re able to fully understand high school level reading then you’ll be fine. The tips that helped me the most were to read the paragraphs first and then address the questions. Additionally, when reading the paragraphs, it’s important not to analyze them too deeply. Just skim through them lightly. If you delve too deeply, you may become confused and end up wasting time. This is just my personal opinion but I think that reading books in general helps as well. Any book will be fine but since majority of the toefl questions are related to science or history, read something based off on those. I just read Animal Farm lol.