Contest strategies
Although all math competitions require knowledge of math (duh...) to do well in, there are certain ways to do slightly better than normally using some contest strategies.
General Strategies
Skipping Problems
Instead of spending twenty minutes on a problem, some people choose to spend thirty seconds reading the problem, then skip it. The time saved skipping the problem can help you check and solve other problems, and you can always return to the problem that you skipped. This concept helps double where you are rewarded for a blank answer, such as the SAT, the AMC 10, and the AMC 12.
In the MathCounts Sprint competition of 2006, many of the harder problems were presented earlier on in the test, putting people who did not skip problems at a large disadvantage - Daesun Yim, the 5th place written finisher, skipped five out of thirty problems on the Sprint round, and he only got two of the twenty-five problems he answered wrong.
Educated Guessing
Educated guessing is the art of taking a, well, educated guess. An educated guess takes less time than completely solving the problem, especially the problem stumps you, and if you can narrow the problem down to a couple of choices, you may be able to take a good guess, saving you time and giving you a chance of getting the answer correct. This tactic helps the most in competitions with multiple choice answers. It also helps where a wrong answer and an answer left blank are counted as the same amount of points, such as the AMC 8 and MathCounts.