Put your vocabulary on the top shelf of your toolbox, and don't make any conscious effort to improve it... 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 shot ones. This is like dressing up a household pet in evening clothes. The pet is embarrassed and the person who committed this act of pre-meditated cuteness should be even more embarrassed. Make yourself a solemn promise right now that you'll never use 'emolument' when you mean 'tip' and you'll never say 'John stopped long enough to perform an act of excretion' when you mean 'John stopped long enough to take a shit'. If you believe 'take a shit' would be considered offensive or inappropriate by your audience, feel free to say 'John stopped long enough to move his bowels'...
Stephen King, On Writing: A Memoir of the Craft
humour