It really depends on what kind of issues you have right now. Have you talked with your teacher about it?
In terms of problem-solving skills, assuming you know your methods.
I often say people struggled with maths mostly because they don't read carefully. 99.99% of the time, the question will contain all and the only information you'll ever need to solve the problem. So if you happen to get stuck, see what information you haven't used, and usually there is breakthrough.
Also chunking (I think that's what's called) - i.e. identifying the mini problems within a problem, and solve them one by one. For instance, say you were asked to find the equation for a straight line. This problem can be further divvied up into two mini problems - (i) find the slope of the line; and (ii) locate one point lying on the line. Usually one is trickier than the other to find.
Also do note that knowing the maths and doing well in exams are two related, but wildly different ideas.