Rather than flatly describing sights, sounds and smells, provide contours by showing us the emotional responses of your characters as well.
From A Game for the Living by Patricia Highsmith:
The boy nodded and licked his thin lips. The sight of his tongue near the soft moustache was peculiarly disgusting to Theodore.
An entirely irrelevant detail of the boy has become a character trait for Theodore, and we can feel an unsteady current in the subtext.