If you are aware that maths is not your forte, then you need to take more effort
right in the classroom. Make a conscious effort to attend the lecture if your
mind tends to wander. Even if you understand the material, you have to take
notes to refer to them later.
One tip is to try to solve the problem on your own while the instructor is demonstrating it. This exercise is a good practice that will also help you to stay alert.
Keep a separate page with all the formulas, so you do not have to scour the
notes whenever you need them. And as you know, practice
makes perfect. The more you can work out problems, the better equipped
you will be to handle any variations of questions on the test.