Now, please don't take any of this the wrong way. I am not a stalker. I am certainly a normal person. But, there is something which I do sometimes to help with description. Description, I find, is the part of my writing which I leave out the most. I think of my characters as just people, regardless of what they look like. Now, while this may be a very inclusive outlook on life, it does not make for as immersive an experience as I would like.
So, what to do if your characters all look the same? Just look around you. When I am on the bus, sometimes I will surreptitiously look at the people around me and think about how I would describe them. What does their hair look like? How would I bring to life that particular set of features on paper? Here, for example, is a man who regularly takes the same bus as I do:
He was a tall man; not particularly heavily built but with enough bulk to be noticeable. He had his eyes closed, and his eyelashes and lips were almost feminine in contrast to the rough stubble which covered his chin. He did not, however, look effeminate. On the contrary, his features combined in a face which looked astonishingly manly.
Hardly the best of descriptions, I know. The difference, however, is that I would never have come up with something like that all on my own. If it were me, I would have simply made up a man. But what is a man without a few curious features. And don't stop there. Try to imagine what kind of job they do. Are they unemployed? Married? A lawyer? A doctor? What is their personality like? The beauty with this is that they can be whatever you want them to be. Such as:
He spent most of his days at the university, leaving early and coming back late. He did not enjoy the commute; in fact he spent most of those times trying to sleep on the bus, with his music in his ears and trying to ignore the movement of the bus.
And that, I believe, is all I have to say on the topic. Try it guys, just try not to let anyone see you staring. They probably won't comment, but you'll be forever marked as the strange person as the bus. Though if you're like me, you were probably already strange to begin with. Bye!