- Study hard.
- Try not to make careless mistakes.
- Ask the teacher for help if you need it, that is what they're there for!
- Engage in class, show your teacher you engage and pay attention.
- Practice. Part of excelling in Math is understanding the material, and part is just being able to recognize which method applies to the particular problem that you are solving. The only way to hone that skill is to practice - eg. do all of the assigned problems.
Remember to try as hard as you can. Depending on the level of math course you are in, sometimes it helps to study in groups, and get in with someone who seems to understand the material. And of course, there are several members here on WikiAnswers that like to help.