I wrote this post in another blog a couple of years ago and thought I should share this here as well:
If you are going to statistically analyse your data, knowing the right statistical test is absolutely essential. However, even if you have taken a couple of statistical courses, it is often difficult to decide which ones are the most relevant or correct tests.
If you are in that position you might find these links useful:
Don't be surprised if your data can be analysed in many different ways depending on your objectives and hypotheses.