You might look at this site to get started:
It also depends a lot on the context, and how the site is being used as evidence. Some questions to ask yourself when reviewing a site:
1. Does the author link to other sources of information as back up for claims? Or do they just assert opinions without any backup whatsoever?
2. Does the author make claims that can be corraborated by others, or are they singular experiences? For example, the claim, "I saw a shiny object
near the moon last night at 1:30am," could be checked by multiple people to see if a conclusion can be drawn about what was seen. A claim such as,
"Grey aliens visited me in my bedroom last night, but I forgot to take pictures," is a little harder to substantiate.
3. Information published in peer reviewed publications tends to be stronger than not because multiple people have read, analyzed, and dissected the
argument and conclusions of the author before publication.
4. Although you want to beware of genetic fallacies (a logical fallacy where one discredits a claim solely based on the source of information), it
can be a handy tool to begin analyzing a specific claim. For example, if a website argues that the Republican agenda is bad for America, and this
page is on the Democratic National Committee site, you might want to take stronger look at their argument.