You may explore more fully the various tactics in the pages linked from the navigation menu. The tactics described in this guide should be practiced repeatedly and in coordination with each other, such that they become a set of habits and dispositions toward sources of information, much like those described in the ACRL Framework for Information Literacy for Higher Education. But, as you start out, it is worthwhile to try out each tactic separately and hone your skill.
When you encounter a piece of information online (a factual claim, a picture or video used as evidence, a news article from an unfamiliar source, an argument about a current event or issue, a meme quote, etc.), you can evaluate that information for validity and credibility by following these tactics:
Stop (or slow down) and adopt a skeptical (not cynical) attitude toward the information
Read laterally by going away from the information source and finding a trusted source that can corroborate or provide more context for the information
Make it a habit to slow down and be mindful about the information you engage with and consume. Exercise restraint when you encounter suspicious information. Avoid clicking on "click bait," clicking on only the first search result, or sharing information within your social networks until after you have read laterally and confirmed the credibility of information.
Be mindful of the strengths and dangers of social media for finding news and information and participating in public discourse. Social media platforms are designed to make a profit off of your attention and "engagement" by selling your attention to advertisers, and thus they encourage "engagement" at all costs, including at the cost of trusted information and balanced coverage of issues.