Depends how cartoony a look you're going for. There's no "magical" way to take a photo and make it into a traditional, mickey mouse-type cartoon.
You can achieve a passable cell-shading look by using the cutout filter. My suggestion is to check out the other threads in this forum on the subject. There have been a half-dozen or so in the past couple days. There may be other tidbits of advice in those threads.