Icon and Avatar Cropping Tips

The crop tool allows you to select an area of an image and discard everything else outside this area. When making icon, some people like to crop first then proceed to do the coloring from there. If you ask me, I do cropping in the end. Why? well, because I can do the coloring on one image and just crop them differently to get 4 to 5 icons...maybe more. So now, the question is...what is a good