There are a lot things you need to keep in mind when you are choosing sources for an argumentative essay.  The sources you choose as a writer will ultimately go to your credibility as a writer, and when you are writing an argument in particular, the opposing side is always looking for ways to discredit you.  Not only does your argument have be bullet proof, but your sources do too.

The first thing that you must consider when choosing a source is the credibility of the source itself.  Is it from a reputable website or book?  Is it known as being biased towards one way or the other?  You also have to think about how relevant the source is to what you are talking about.  Is it recent enough to be applicable?  Does what it is saying go to help you prove your thesis?  If your source meets these simple standards then it is likely that it is a good source for you to use.  Your choice of sources can be the make or break of your paper.  With reputable sources as the concrete foundation of your paper, you are off to a good start.