
I have many different ways of working from thumbnail, to sketch, to final. In this instance I had the added challenge of getting a likeness of a character linked to a specific real person. So I gathered reference after the thumbnail (which I do not always do). When I got this job I was very excited because I am a fan of the Kolchak tv series and Darren McGavin. However, I knew this was going to be a challenge because both the A.D. and I wanted it to look like Mr. McGavin. So after coming up with a thumbnail I liked, I went and got the DVDs of the

first two Kolchak TV movies (much nicer
looking and cinematic than the later series)
and combed it for shots that would fit my thumbnail. I couldn't find the exact shot I wanted, but I found two that when pieced together would work. The next step was to shoot myself in a similar pose to Kolchak because I wanted more information to work with than the screen shots gave me. I also searched the internet for the camera that he used, I never found the exact one, but I did find a similar model.

I have now put together the reference I need, next the trick was to get what I needed out of the ref. I started with a rough lay-in from the screen grabs. Then, using the photos of myself and my own sense of idealization I began to redesign and render. I wanted to push a bit more of a tough rugged Clint Eastwood, or Tommy Lee Jones look, so I added a bit more structure to the face (especially the nose and chin) and squared off the jaw a little more. I also wanted more of a stern look to his squint, so I furrowed the brow and deepened the creases. I used the ref of me quite a bit in the hands, and tilted the shoulders to give a sense of movement. The challenge was to do all of this while maintaining the likeness.
After finishing up, I then paint the final illustration primarily from the final sketch. I only refer back to the photos if I need a little more information. This was a pretty tight sketch so I don't remember doing that too much here.
EDIT:
I was asked about the "zombie", here is the reference for him. It's me again, and an anatomical head used as ref to help zombify me. I normally just make up the zombification, but I wanted a very real, almost clinical look to this guy. I also distorted the proportion in the shadow to give him a quirky, supernatural vibe.