Expressing yourself in new and interesting ways goes beyond simply acquiring new words. In fact, you can upgrade your verbal acumen without learning any new words at all. You simply package what words you have in different ways, i.e., come up with new phrases that feature the old words.
For example, yank the word chagrin out of the old, worn-out phrase "much to my chagrin" and try using it in a refreshing, new way. To do that, you have to go find out what chagrin really means and think hard about how it can be used. Normally, I would suggest that you look to see how others use it, but, as is the case with all the words in this challenge, it's not often used in any other way.
After you've whooped chagrin,* try liberating the underlined words from these overworked phrases:
assuage your fears
cast aspersions
beyond reproach
daunting task
regale you with a story/song
rue the day
with much aplomb
run amok
hate monger
redress a grievance
rank amateur
__________
* In the late '60s, my mother delighted in sending me off to school in full chagrin and the latest in home-manufactured psychedelic sartory.