The first thing that I learned was that it was actually a lot easier than I thought it would be. I always thought that the person would be traced out and then turned into a cartoon step by step. I'm sure there are many ways to go about it but the way that I learned was by using the filter gallery. The filter is called Poster edges. It does all the work for you and you can adjust some levels to make it look exactly how you want.  I also learned about color halftones and high pass levels. They allowed me to change shadows, contrast, and exposure so I could make the person pop with the background.