There are a number of criteria to consider when evaluating whether or not a source is reliable and appropriate to use as evidence. Answering the following questions can help you determine whether or not a source is reliable.
What type of source is this (e.g., article from a journal, magazine, newspaper, website)?
Does your topic require current information?
When was the source published? Is it current for your topic?
If it is a website, when was it last updated?
If your source cites any other sources, are they recent as well?
What are the author's credentials or background in this area?
Has the author written other things on the same topic?
Does the author OR publisher have financial interest in the topic?
Does the author's background/publisher information make the source more or less credible?
Is the information primarily fact or opinion?
Does the author present multiple sides (pros & cons) of the issue?
Is the information supported by research?
Are there citations?
Has the author provided sufficient evidence?
Based on your response to the above questions, do you think your source is highly biased or minimally biased?
How do you plan to use this source?
To support a particular point you are making?
To explain why your solution is the best option?
To explain how your solution works?
Based on your answers to the questions above, do you think this source is reliable?