There are 3 important questions to answer when evaluating sources:
Who's behind the information?
What's the evidence?
What do other sources say?
Below, you'll find 3 assignments to help you practice each skill. Then, you need to ask these 3 questions of your own research before moving on.
If there's a problem with one or more of your sources, it's better to find another source now, rather then after you've started writing.