Use the apostrophe in it's proper place. Avoid colloquial stuff, like totally. Avoid those run-on sentences you know the ones they stop and then start again they should be separated with semicolons. The passive voice should be used infrequently. And don't start sentences with a conjunction.
Exaggeration is a million times worse than understatement.
Stamp out and eliminate redundancy because, if you reread your work, you will find on rereading that a great deal of repetition can be avoided by rereading and editing, so reread your work and improve it by editing out the repetition you noticed during the rereading. It's incumbent on one to employ the vernacular and eschew archaisms.