Choose someone who knows the subject. Enhance in your knowledge with a good mentor.

I strongly recommend him to anybody who is looking to improve his academics, he doesn't rush and teaches at a pace that is good for every student. If he spots someone lagging he gives them extra attention and makes sure they catch up. He is also very qualified in terms of knowledge as he himself has cracked tough exams which require high level of mathematics, which makes him trustworthy.

Explains well and in simple language. Have a deep knowledge of the subject.