A picture is worth 1000 words, right? But how do you know if the picture is of what the author says it is? What if the image was taken somewhere else entirely, or at a different time? How could you check? Two techniques you can use are Reverse Image Searches and Google Maps.
With a reverse image search, you can search the internet to see if that same photo has appeared in other places. If the same photo is being used in multiple articles or memes to represent different places or events, then it could mean something's fishy. See if you can track down the origin of the photo with a reverse image search!
Does someone claim that a photograph is of a particular location? Search for the location on Google Maps and see for yourself! Can you find the same landmarks? The same shops or buildings? Here is a photo of the intersection of W 59th Street and 6th Avenue in Manhattan, New York.
...but is it, really? Use street view in Google Maps to take a look around. What can you find out? Where was this image taken? Or, hard mode - can you determine approximately when it was taken?
Two kinds of photos to pay close attention to are those with people holding signs and those with people wearing clothing with text. These sorts of images are easily altered using photo editing programs. Reverse Image Searching works well to determine if the same photo can be found with different text.