Write about the object or subject using your sense based faculties; Taste, Touch, Sight, Sound, Smell as well as your kinesthetic senses- movement and body sensations.
Set your stop watch and write for ten minutes - EXACTLY!
Clashing metaphors
A metaphor is "something used, or regarded as being used, to represent something else"... so pick a word and set your clock for 5 minutes [it might not take that long] and use the 5 senses, for example a license plate tastes like a..... dentists drill! See where it goes. Stuck for a word? Try the Random Word Generator at coyotecult.com