Be a lurker, a stalker and watch the gestures, the movements of people around you.
Note what makes them stand out. Unusual traits or interesting habits, that is.
Use these gestures in you manuscript to define your characters and bring them to life. Everyone has their quirks. Harvest from people around you to make the storyline bloom.
Family and friends roll their eyes when they see me taking notes, but use care not to spook total strangers. It makes them nervous.
And that restraining order really sucks too.