Connotations: Be careful of words that carry implications, associations or nuances of meaning that conflict with your message. Connotations are subjective and are usually culturally or emotionally based.
Abbreviations/acronyms/colloquialisms/Jargon: If you believe your audience will recognize them, use these devices to cut down on wordiness and possibly gain rapport with your listeners/readers.
Just make sure you write out the full reference in your text before resorting to the shortened abbreviation or acronym.
If you're not positive your audience will recognize certain colloquialisms or jargon, figure out a way to make it clear to the reader or avoid them.