Understatement is always best. Analogies in writing are like feathers on a snake. The passive voice is to be avoided. Go around the barn at high noon to avoid colloquialisms. Even if a mixed metaphor sings, it should be derailed.
Exaggeration is a billion times worse than understatement.
Don't never use a double negation. Verbs have to agree with their subjects. Proofread carefully to see if you words out. If you reread your work, you can find on rereading a great deal of repetition can be avoided by rereading and editing. A writer must not shift your point of view.