After investigating the credentials of the author or creator of the information, and the accuracy of the claims they are making, the next step is to investigate their objectives. What did they hope to accomplish by creating the information?
Information is created for many purposes, good and bad. Academic work intends to broaden understanding. Advertisements intend to sell something. Satirical sites intend to amuse. Malicious sites intend to deceive. Partisan pieces intend to convince others or reassure their own side. And so on.
Information with a purpose.
(While certainly "tasteless," this creepy ad is actually for a good product!)
Most of these things aren't bad in themselves, but context is everything. Misunderstanding a hilarious satire as a truth piece can have embarrassing consequences, for instance. (But that satire could be a good source in the right context; after all, I just linked to an Onion piece as an example of a satire, didn't I?)
Ask yourself: why was this piece of information created? Consciously thinking about a source's objectives is one of the most important things you can do to to raise your defenses against satire, charlatans, and soapboxes.
Lately, you've noticed some inspirational memes floating around like these:
Each bears a Facebook address: "fb/david avocado wolfe." Curious, you investigate the site and the man behind it.
What is the objective of these memes? What is the objective of the site from which they originate?