I noticed on retreat this past week each of the 20 or so monks I saw three times a day at services had a distinctive walk. Some of it had to do with footwear, some of it with age and ability. They all wore variations on the same clothing but they carried those robes quite differently. Their heads sat on their necks in particular ways, their necks sat on their bodies each quite differently. Their ways of kneeling, of bowing in prayer, in standing at attention were different. The way they held themselves when they sang varied amazingly.
It was a rich visual field and I could have created a dozen characters. So next time you can, watch a crowd of people, say at the mall. Rather than looking for a general impression, notice one thing at a time. How do the next 15 people walk? What verbs describe that? What comparisons can you make?
You can also do this while watching a movie or a TV show. How would you describe for a reader the way this man moves or gestures. Actors are a great resource for writers for they have studied and honed the gestures and tics and mannerisms that make a character come alive. If we can learn to translate that to the page, we can create lively, memorable characters.