I used a review book by McGraw-Hill that prepares for multiple different nursing entrance exams (I got a 93.3) but ATI has a book that's just for the TEAS, which a few of my friends used (They got between 70 and 86). I also studied my notes from my science classes.
The math portion tests basic skills like adding, multiplication and division, word problems and reading graphs and charts, I've had up to calc 2 so my background was really strong for that portion. If you're someone who struggles with math, just practice problems until you get stronger or feel more confident. For the reading comprehension and grammar, go over grammar rules, spelling, test your vocab skills, practice identifying main topics, styles of writing, subjects, clauses, correcting errors, punctuation and whatever else you might be weak in. Now the science is a little harder because its so broad and covers so many different areas so definitely use a review book for this, don't skip out and if you're low on money, try to find a used one.
Start reviewing early, I waited until a few days before and stressed myself out more than I needed to (I was taking 3 summer classes at the same time so I overloaded myself). Take practice tests so you know how you'll do time-wise but don't rush yourself, I was the last person to leave my testing site because I utilized all my time. If you're stuck on a problem, move on then go back to it so you can get through the whole section. Read carefully and jot down notes if it helps you. Don't stress yourself out and just do your best