What does the smell do?
One reason why smell is hard to describe is that, well, the English language does not have the largest vocabulary for it. But a writer must expand beyond simple words, using nouns, verbs, and metaphors to turn smell into the powerful sense it is.
Ivan Siarbolin said it well:
"Visualise what the smell does. Does it creep into your nose? Wrap around you? Follow you? Make you fly?"
Thus, describing smells can be a fantastic opportunity to display your creativity.
A disgusting smell may choke you. A rose could have a soft, quiet scent. A graveyard could smell of longing. A young boy may smell of lemons.