This is a test of commonsense. Complete the next sentence:

How to tutor mathematics
Know the material.
If you know algebra really well, but are not as strong in calculus, only tutor algebra. Your students are learning from you and they can't do that if you don't know the material inside and out.
You also want to make sure you know the math standards that your student is expected to be proficient in. If you can't solve all of the problems your student presents you, you shouldn't be tutoring the subject.