I went from a 26 (April junior year) to a 33 (Sept. senior year), so let me give you my take on your situation.
MATH: This is your really bad section, so put around 40-50% of your efforts here. Basically, the math section has dominantly recurring concepts - it’s not some crazy stuff you’ve never seen before. That being said, go for the basics. I’m not sure if your issue was accuracy or actually understanding the question, but I’d say that nailing the main areas (like geometry, basic algebra, trig/triangles, number theory, etc.) will really push you into the 30’s. The ACT Red Book (from the official makers of the test) does an awesome job with the math section and with hammering the basics.
ENGLISH: Another one of your weaknesses. I’d say focus 25-35% of your time here. This one came naturally to me, but in your case I’d suggest going through a full practice test and see what areas mess you up. Even online places like VarsityTutors are good for the English section (they suck for other sections though, so just use it for English). If you’re struggling with grammar, then google or research some of the grammar rules you’re missing and write them down. Mentally plugging A,B,C, and D into each sentence/question also really helps, if you have the time for that. If it’s the content questions you’re struggling with, then I’d suggest reading the answer choices first and then making sense of each one with respect to the paragraph/passage. Focus on the message the author’s trying to convey.
SCIENCE: Get “For the Love of ACT Science.” It’s an awesome book, and it got me from a 23 to a 34 in Science. If that’s not possible, then just take this advice: “Skip the passage and go straight to the questions, and if a question doesn’t make sense, then just read the answers.” Usually the answers are often the questions disguised themselves, and that saves you a ton of time. Save the “arguing scientists” passage for last - and for that passage, you just read the intro, the first sentence of each scientist’s claim, and then go to the questions.
READING: You seem pretty solid here, so great job. If you wanna go higher, then really focus on inference and understanding the author’s intention/tone - those are usually the higher-level questions that are missed.
Oh, and definitely get some sleep! Taking the test tired is the worst, since the ACT is very fast-paced and you need to constantly be on your A-game when it comes to attention. Maybe have some coffee in the morning, it helps me stay alert throughout the exam.
Good luck! PM me if you have questions. You got this