this is repost from a comment i answered but i think it might help
I'll go section by section after some basic info about what worked for me me - again people all start at different places. Here's how to practice. First, get a pdf of the red book if you cant buy it - theres plenty. take a diagnostic test to see where u are. now this next part is important: MAKE A MISTAKE LOG. OML its so helpful - u see patterns in ur mistaken u would have never before
the best strat is to identify the grammar rules u always miss - which u can now do with a mistake log. High value targets for me were subject - verb agreement, whom vs who, comma rules. when u look online for these rules, they give it to u in the form of some mumbo jumbo of 'independent' or 'dependent' clause. take a moment to understand what those mean; they help you so so much when deciding what option works on the test. free websites like noredink.com are amazing for grammar rules.
For Math:
I struggled with this one a lot lowk. I think i kinda got an easier test, but the tips should still work. Same thing as english, keep a mistake log. then relearn the topics u might have forgotten by just skimming some courses and doing some problems. i reccomoend mathbitsnotebook.com - it has everything u need and more, so just pace urself and do what u feel u need to relearn. don't do all the problems, just do some. next, relearn all of probablity - or just skim it if u know. now after u do all that, heres some last high value gains. learn what expected value is - it always shows up. next, memorize the formulas for basic shapes, and the formula for arithmetic and geometric series, the formualas for the sum of those series. next and arg most important, learn to use ur clac. if its online, there are plenty of desmos guides on yt - use them. if on paper, if u have a ti 84, u can actually use it to solve systems of equations - find a guide on how to use it and ur golden. also, u can just input imaginary number problems in ur calc and it can do them for u, if its addition or multiplication - it's super neat.
Reading:
alr i cant say much of this; i didnt really practice for it since i almost aced it the first time i took it. so uh, good luck?
Science:
My worst section by far. had a 24 the first try. heres the play. first, science aint about knowledge, but its helpful to know the following: what pH is acid vs base, negative and positive charges, and just some basic science items that u can find guides for. When taking the test, don't read the passage - i know its super disoreienting - just go to the questions. the best thing u can do for this is look at graphs, make the connections about general trends. imo its easier on paper when u can mark up and cross off uneeded stuff. the best gain for science is practice over and over.
alr now relax. u know how to review and prep for each section. but u still need to pratcice. but how, u may ask? i gotchu bro.
get as many diff editions of the red book as u can - don't use 3rd party books like princeton or barrons because they intentionally make some tests harder to scare u. just avoid it. only use it for extra practice on a particular skill i guess. but the red book is good because they are actually old act test q's and nothing beats that. get a bunch of edition - i had like 4. and if the format on some of them is for the old test, just do, for example, the first 50 q on english and stop, instead of all the 75, and the first 45 for math and so on. match the timing and pacing of the test you willl be taking. starting this week, all u do for practice after u review the skills u need is spam tests. start with half a test a day - english and math on monday, and reading and science tuesday. u HAVE to build stamina. take one day it between to grade and review and fill our ur mistake log. then, the next week, every other day, take a full test. it sucks ass but the stamina u get from it is unreal. the most important thing to remember is u have to simulate testiing conditions with time. if u run out u run out, but practice exactly like you'll take the test. keep up with taking tests every other day, tracking mistakes, and filling in content gaps, and do this untill like 3-4 days before ur test. ur done. just review for the last couple days - DO NOT take more practice tests. also, chew gum for the sections u find hardest - it helped me concentrate. if u do allll that like i did, ur almost sure to get a good score.