Austin Kleon with some excellent advice: "Go to Goodwill and buy a gigantic used paper dictionary for $5 and keep it on your desk."
When you're looking for a word to replace a word in your writing, John McPhee suggests skipping the thesaurus and going straight to the dictionary: "With dictionaries, I spend a great deal more time looking up words I know than words I have never heard of—at least ninety-nine to one. The dictionary definitions of words you are trying to replace are far more likely to help you out than a scattershot wad from a thesaurus."
The dictionary not only gives you a gives you a list synonyms for the word you're looking up, it also gives you a deeper understanding of the meaning of the word, and sometimes the definition can lead you to a better way of phrasing altogether. (Stephen King: "Any word you have to hunt for in a thesaurus is the wrong word.")
There are benefits to spending a little more to grab a copy of the Oxford Dictionary of English or Merriam-Websters; note that the ODE is not the OED [Amazon] which is on another level of logophilia entirely. Get it as well.