1. Learn formulas for that particular topic. 2. After learning formulas try to solve some problems. After once solving such problems you should solve problems for which you dont have solutions. Without interest you cant buildup concentration. Buildup interest by learning formulas.
Depends on the type of math you ate doing. If you are doing algebra focus on the formula and if you are doing arithmetic then focus on what ever you are doing. Don't listen to music while doing maths and the best time for doing maths is early in the morning. If you are not able to concentrate on maths leave it then and there and try it again later