The best way to learn proper English is to read news report, and watch news on TV. Watching TV shows is a great way to learn casual English, slang words, understand culture reference and humor. If you have already watched these shows then you may recall the words used in the following dialogs.

a COMMONER like me
slaps a little lord like you,
Game of Thrones Season 4, Episode 4

how do they punish a COMMONER
who strikes a prince?
Game of Thrones Season 5, Episode 9

lf you're going to pose as a COMMONER,
you should do it properly.
Game of Thrones Season 2, Episode 7

From Lorathi COMMONER to the Red Keep
in 10 years,
Game of Thrones Season 2, Episode 9

Were you a COMMONER, I'd have
you shipped to Valyria at once
Game of Thrones Season 7, Episode 2