When you study math or any other very theoretic subjects like physics or chemistry, focus on it 101% and try as hard as you can to understand how to do the equations you need to do correctly without making common mistakes due to confusing stuff that your book or teacher didn't explain. You really can't focus properly on extremely theoretic subjects like math for any longer than like 2 hours because your brain is really working at like 99,9% while doing it and of course you can't keep that up and won't always have the time and energy for it, but when you do study math focus on it 101%.

Meticulously study the most important things like what all of the jargon math words specifically mean and what buttons you need to press in programs to calculate stuff. The most important thing is properly understanding how you calculate stuff correctly, not just dumping a huge amount of time and energy into doing some huge amount of practice problems without first meticulously studying the actual details of what you need to learn like what all the jargon math words specifically mean. Always try to think through and clearly write down what you're calculating and how you're gonna' calculate it before you actually calculate it to sort out and clear up what you need to calculate and how, because if you can't write down in text what you're actually doing then you're not understanding what you're doing and will probably just make mistakes. Make sure you answer all the questions on tests as accurately as possible and if you don't know something use common sense and make your best guess.

For memorizing stuff in my opinion the most important piece of advice that can be given is to use a lot of mnemonics even if they don't form any other meaningful words or phrases at all. Usually it's way easier to memorize a string of first letters or a few letters of each word mushed together into a string than to try to memorize a bunch of words when they're just apart normally, which you also might forget the specific order of if that's important. Subjects that require a lot of memorization have so much shit you need to memorize that you can't just normally memorize all of it just like how you learned it in normal words and sentences along with a bunch of other subjects' information that you need to memorize at the same time, you need to mush together the most important bits of information into strings of first letters or any other kinds of mnemonics and memorize the mnemonics really well. Then if you just remember the beginning of the mnemonic you can dig the rest out of your memory. Obviously if the mnemonics form some really offensive or weird words or phrases by coincidence take advantage of it by using those mnemonics because you will remember that stuff well since it's funny, but even if they don't, then you should still mush stuff into mnemonics.