Smell is one of the most often overlooked senses in fiction, yet it can be one of the most powerfully evocative if used well. Including the scents present in a scene can be used to add texture, depth and even personality.
The problem, quite often, is how do you describe it? Let’s say your character is at a fishmongers. “The air smelled of fish.” Not exactly poetic, and certainly not adding anything that describing the look and feel of the place (bulging eyes, a chill from the ice, etc.) couldn’t do better.
“People quite often associate a particular smell with a particular memory.”
There are a couple of options. The first is to use smell to add just a little character to an otherwise bland description. In the book I’m reading, one of the main characters wears sandalwood perfume. The fragrance is dropped in occasionally to help add to his charm. The second option is to say what thoughts the smell evokes in the POV character, rather than what it actually smells like. That fishmongers? Maybe it smells like holidays by the sea as a child, or the harbour where they met the strange old man. People quite often associate a particular smell with a particular memory.