If you want a concise guide to get you up to speed, then look at Ivan Savov's two books. One is the No B.S. Guide To Math And Physics, the other, No B.S. Guide To Linear Algebra.
You know this already but I'll say it anyway, you have to put in the practice by actually doing the problems. It is the only way you learn it, so it becomes second nature. You do have to apply yourself. Maths is very difficult to catch up, if you let it slip too far.
Trying to cram everything at the last moment is pointless, learning maths doesn't work like that. It's a building process. There are no shortcuts, you always get found out in tests.
College or university maths, is a much bigger step up again over high school. A greater workload and harder.
I'm not trying to scare, or put you off, but college will eat you alive if you don't get a handle of it from day one. You must develop an effective study program and stick to it.
Good luck, I hope you do well.