You are a very talented painter. I am envious. Now that the compliment is out of the way...MAN artists use that Kirk headshot as a reference WAY too much. Every time someone has to paint Kirk they find that 8x10 on Google. If you ever have to paint more Kirk, visit TrekCore.com. They have many a screen shot of each episode. Tones of unique angles!
As a trek fan, I understand and even share your frustration. There seems to be 3 shots of Kirk that are constantly being used because they are constantly asked for. Though I've done many diffrent variations of Kirk myself using screen shots from the show as ref, they are rarely used,published, sold or requested. Perhaps in the next couple of weeks I can post them here. Thanks for the TrekCore suggestion! Much appreciated!