I personally went to a modeling studio and took 200 head shots. We immidiately were able to eliminate 100 of the shots with out to much of a problem. I then took those 100 to some of my friends in Pasadena, After about an hour of looking through them, we made it to the top 30. We then randomly borke them down into three groups of 10. We compared those ten to each other, picking the top 3 from each. I then picked my favorite from the remaining 21.
So that left me with 10 pictures, and a lot of my friends who were sick of looking at me. I thaught all ten pictures were pretty good, but I had to that the random admissions committee would like the pic, so I took the ten to the street, and asked Random people to pick the one that they liked the least. Eventually, I made it down to 2 pictures. I then took those 2 to my then GF in Hollywood, and right before I was to send out my first secondary, she choose here favorite. I then ordered that pic to be mass produced (40) and sent them off with all of my secondaries. In my opinion, time well spent.