Do you have a tendency to use long words in your writing when you don’t need to? Do you write “commence” instead of just “begin”; “in order that” instead of “so”; “numerous” instead of “many”; “utilise” instead of “use”?
If a simple word accurately reflects what you want to say, then use a simple word. Your writing will be clearer and you will sound less pompous. This document from the Plain English Campaign has a list of simple alternatives to unnecessarily complicated words and phrases.