When you find a source, consider these elements to determine if you should use it:
Relevance:
How does this source help me answer my research question?
You'll probably need a number of sources to fully answer your research question. Consider what each source contributes.
Does it provide a perspective or argument that I don't have yet?
Before choosing a source, consider how you'll use it and how it relates to other sources you've found.
Does it support my argument? Does it represent an opposing argument?
Some sources might provide evidence or context for your argument. Other sources might help you represent another viewpoint.
Does it provide basic or background information about my topic?
Books and newspaper articles are useful for finding background or basic information about a topic. Scholarly research articles are typically too complex to provide this.
Purpose:
Is it intended to persuade, inform/educate, entertain, sell, or some other purpose?
If you think it's intended to entertain or sell, consider if it's appropriate for academic research.
Who is the audience? Is it written for other experts, or a general audience?
Consider who your audience is and try to find sources that would appeal to them.
Author:
Can I describe the credentials of the author? Are those credentials relevant to my topic?
A quick internet search can tell you a lot about an author.
Does the author use biased or prejudiced language? Is the author trying to stir emotions?
Try to find sources that are being objective and don't use strong or emotional language.
Context:
Was the source published recently or is it older? What has changed about my topic since it was published?
Unless your topic is historical in nature, you'll probably want to use the most recent information you can find.
Where was it published? What is the mission or focus of that publisher?
Research the publisher on the internet, if you're not sure. Consider that's publisher's purpose and whether it's appropriate for your topic.
Evidence
What evidence does the author use to support their argument? If they cite others, are those experts on your topic? Can you identify where their evidence comes from?
If you're not sure if the evidence is valid, try to verify it using another source.
Do they describe their research methods in detail?
Scholarly research articles will often describe their research methods thoroughly. Other types of sources might summarize the research of others, which is okay if they cite their sources.
Do they cite their sources? If you needed to, could you find and read those sources?