This tutorial is for photoshop users, although some techniques used may be useful to those of you who have other image editing software.
Step 1
Find the image you would like to make an icon out of. For the tutorial I chose this one:

I try to get my base images as large as possible or at least get them to be good quality. One important part of making icons for me is to have high quality images, and a high quality final result.
Step 2 >>