Oddman's answer is amazing, and if you follow his advice you will do extremely well with math. The only thing I would add is whenever possible Draw a diagram. If you can see what it is you are doing, it will make most question seem so straigt forward.
Keep practising!If a particular world problem is too hard,draw you models.Models are like the summary of a book.It helps to have a clearer mind of what the question is asking.Try to remember your tables and NEVER make careless mistakes.Try to find books in the library that teaches shortcuts so you would have more time to check.Do not rush and do not try to be the first to finish.And your handwriting must be clear enough to see the numbers and workings.If not,you would lose marks.I hope this was what you were looking for!
Good advice, here are other points.Do a lot of exercises, and do them very clean, i.e. Write every step in the transformation, writing aside or between formulas, the rules you used to rewrite the formula.Do not try to use the rules randomly, focus on your target, and try to use the rules that transforms your formula closer to the desired goal.If you have problems with proofs, I recommend you to read some book, like Daniel Solow How to do an read proofs in mathematics. Or Velleman's book with a similar title.