Miss Cellania has an oldie but goodie list of literary rules (the sort of thing that circulated on Usenet). Here are a few:
* Prepositions are not words to end sentences with.
* And don't start a sentence with a conjunction.
* Exaggeration is a billion times worse than understatement.
* Do not be redundant; do not use more words than necessary; it's highly superfluous.
*One should NEVER generalize.
Always avoid alliteration!
I think I'd be willing to take that one literally. No one ever made an understatement accompanied by numerous exclamation marks.