Rule #1:
Never use a word unless you are sure it is the right one. Big or small.
Rule #2:
Use the smallest word possible that precisely expresses your idea.
Rule #3:
A robot must protect its own existence as long as such protection does not conflict with a higher order law. Heheheh.
When I was a kid I started reading earlier and more than the majority of my peers. My vocabulary expanded much faster than theirs. I started using big words in order to impress peers and adults. Now, this annoying vocabulary is my naturall pattern of speech, and I wish it wasn't. I had a GF who was a poet, and she introduced me to how precise and beautiful simple language can be. Since then I've made an effort to use smaller words, as long as I don't sacrifice meaning. It's a lot harder to do than to spout off multisyllabically. When I'm drunk, I can usually be found alienating most of my friends by spewing unneccessarily long words in order to further my self-satisfying rants about politics, economics and the state of my local's taps. I sound like an asshole. I am much happier with my speech and writing when I can express ideas with simple speech.