are you getting questions wrong, or just not even knowing how to approach them?
if its the second one, just do some exams with your notes and text book, or even with the answers, and then work through and make sure you understand them. look at the answers for how you'd do it, then write it all out, steps etc, and hopefully when a similiar question pops up you'll know what to do
if you're getting questions wrong, is it because of silly arithmatic mistakes, or are you doing the question in a completely disastrous way? if its artithmatic, make sureyou always check your working really thoroughly. its its the latter.. you probably need to go through it with a teacher or get a session with a tutor who can explain and you can work out where you're going wrong