Give a quick explanation as to what "edits" are.
Generally, an edit is when you take a recorded and released song, and re-arrange it structurally to make the track more dynamic. There are no real rules as to how you edit the track, but the point is to make it either better than the original (by rearranging sections, removing unwanted parts, and highlighting, or extending the best parts) or to change the vibe of the track with your arrangement choices. You can add effects to create different sound textures and atmospheres, and to a certain degree include exterior sounds to punctuate parts of the track. This borders on remixing, although generally in a remix, you have access to all the individual tracks that comprise a song, whereas in an edit, you are manipulating the track based on the final recorded version. Ultimately you want the track to sound natural and make sonic sense.
What do you look for in a song you're going to edit?
Well, I generally need to get a sense that the song "needs" an edit. Sometimes you find tracks with parts that are so catchy or funky, but ultimately you cannot play them out as a DJ because other parts of the song are downright embarrassing or just kill the vibe of the dance floor completely. Other times the tracks themselves might be well designed with decent components, but leave you wishing that certain parts were extended, certain parts shortened, or perhaps a drum break in the middle of the song would be more suited for the intro, etc. You can completely change the vibe and progression of a song by re-arranging it, and still use all of the original parts. In some cases, an effective edit may mean just taking one or two things out, but conversely, the sky is the limit in terms of how technical you can get in your arrangement.