If we can replace the few words we tend to repeat when we speak or write with synonyms, we will sound well read, educated and competent.
When we have a larger bank of words to draw from, we improve our ability to think and express ourselves. Our thinking will become more fluid and supple. The ability to use words effectively is rewarding.
There are online resources for synonyms. Check these links to get started.
Here is an example:
Synonyms for Significant – Substantial, fairly large, considerable.important,fundamental, profound, noteworthy,remarkable
Of course you have to check for contextual references to see if you can replace the words with synonyms and yet retain the essence of what you want to convey.