One of the really bad things you can do to your writing is to dress up the vocabulary

"Put your vocabulary on the top shelf of your toolbox, and don't make any conscious effort to improve it. (You'll be doing that as you read, of course ... but that comes later.) One of the really bad things you can do to your writing is to dress up the vocabulary, looking for long words because you're maybe a little bit ashamed of your short ones." (#2 p.110)