I know how to do this in a rough and ragged way but I was wondering if there was a standard method. What I do now is convert the photo to grayscale. Then I mess around with the levels and finally the brightness and contrast. From there I trace the bold shades of the new image and repaint the bold shades. Ideally I'd like to get a clean and simple high contrast black/white image which retains the essence of the photo (ie. someones face). The main problem I run into is when I want to add a second or third shade. Is there a good method to divide the converted image into three clear bands of contrast or is it again trial and error?
Have you tried the cut out filter to break the image down into color groups? And then look at your channels to convert to grey scale pick the channel that looks best and press control. A to select and then in layers use the past into command under the edit menu.