Work on practice problems for each topic ranging in levels of difficulty.
When practicing, try to solve the problem on your own first then look at the answer or seek help if you are having trouble.
Mix up the order of the questions from various topics when you are reviewing so you'll learn when to use a specific method/formula.
Make up a sheet with all the formulas you need to know and memorize all the formulas on the sheet.
When you get your exam, write down all the key formulas on the margin of your paper so if you forget them when you're in the middle of the test you can look back at the formula.
Read the directions carefully and don't forget to answer all parts of the question.
Make estimates for your answers... e.g. if you are asked to answer 48 x 12 = ?, you could expect a number around 500 but if you end up with an answer around 5000, you'll know you did something wrong.
Show all your work (especially when partial credit is awarded) and write as legibly as possible.
Even if you know the final answer is wrong, don't erase your entire work because you may get partial credit for using the correct procedure.
Check over your test after you are done with it. If you have time, redo the problems on a separate piece of paper and see if you come up with the same answers the second time around. Look for careless mistakes such as making sure the decimal is in the right place, that you read the directions correctly, that you copied the numbers correctly, that you put a negative sign if it is needed, that your arithmetic is correct and so on.