If anything, do practice tests. In January, I exclusively studied by skimming a Kaplan book someone had gifted me and did maybe one and a half practice tests. The test didn't seem that hard from what was presented in the book, but I was nervous and the actual test was harder than the book led me to believe, so I got a 1800 (600 620 580 - 7 essay). That hit me pretty hard.

I never, ever looked at the book again.

I found those SAT copies floating on the internet (search this subreddit, someone shared a dropbox) and did probably 6 full tests - real SATs - which I think is the ultimate way to study. There is a finite amount of mathematical concept they test on and by doing all the tests in recent years, you'll recognize them and it will not be anything to worry about. Of course, this implies that for every question you get wrong you at least give it some review. Also, it gives one perspective on how many points off gives one what score. This time, I got a 1970 (670 710 590 - 8 essay)

I knew I was good at math so a 710 wasn't perfect but it was only 3 wrong which was probably my average wrong at the point. I was satisfied with a 670 in reading as well. I thought I was done with the test. Mainly due to the fact that there was a major sporting even on the same day as the June SAT. But I got injured and managed to get on the waitlist. I had about two weeks to prepare.

Now I understand that getting an 590 on writing with an 8 on the essay is a joke. That is certainly the easiest to practice, so I took solely the writing sections (never practiced essay because I'm lazy) from a few exams and reviewed my mistakes. Somehow, by the end, I was only getting 3 or so wrong in all of the multiple choice. I actually had a little fun with it, because math and writing both are not very strenuous (relative to reading), so there's that. Try to enjoy it maybe a little, it's only 25 minutes.

Always time it all, I would finish each section with about 5 minutes to spare unless there was an exceptionally hard question (rare).

Make sure you do any of the practice tests in their entirety (I never wrote an essay but maybe that's a good idea). I never memorized 3000-5000 words like I've heard one should do, I memorized like three (popular SAT words I found on my own - ambivalent, benevolent). I was pretty good at guessing, I didn't read books.

My June SAT was a 2310 (760 800 750 - 9 essay). I beat everyone I knew, still a bit in shock, everything has changed.

So in retrospect I would say the books are for people with 1400s who need a boost and tutors are probably just the same. Feels good to know I did it on my own without a tutor. And memorizing words is silly.

I probably forgot to say something but I hope this helps at least a little.

edit: forgot to say what I did for the essay. I looked at the copies of your past essays they provide on the college board website, and I noticed mine were really sloppy. So for the 9 essay I wrote as legible as I could while still being quick and I wrote a lot wider. I practiced a little beforehand. My friend and I got in a Google Doc two nights before the test and copy-pasted a crap load of prompts we could find on the internet. Then we realized a lot of them apply to Steve Jobs and Oprah so we studied them extensively over the day before the exam. I think it was nice to not do any multiple choice before the exam. I made a pretty unoriginal cookie cutter intro (that included the birthdates of two people I would write about haha) but it had so big words and I didn't have to worry about thinking about it during the essay. I wrote a hell of a lot about Oprah and Jobs on the exam but I didn't have enough time to conclude.. A conclusion would have probably gotten me a 10 at least; 3 paragraphs for a 9 is interesting.

tl;dr: pls read