I'm bad at math. How do you do it?

I agree with the above things. And also check your work. That can REALLY help you with your grades.

I never fucking check my work, pineapple that.

Nah, seriously check it. This chick from my chem lab last semester who was not my partner but across from me asked me to help her in calculus a few times to meet up in the library.

I could tell she sucked at math, and the problem was she started understanding some concepts, but then she would pineapple up on the math. And then other problems where she didn't understand the concepts she would just pineapple up completely.

Priority list:
1. If you know the problem and can get it right definitely, do it now.
2. If you remember the type of problem and can probably work it out, do it.
3. If there's a problem you don't really get but it looks sort of familiar, set it up and solve as much as you can.
4. Go back and quickly check 1 and 2.
5. Try to solve 3.

That's how you "check" your work and take (math) tests.