Contractions aren't necessary. One should never generalize. Tell me what you know. Comparisons are as bad as cliches. Be more or less specific.
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.