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.

I am simply a TRADER of spices.
Game of Thrones Season 2, Episode 4

A TRADER from Qarth told me
that dragons come from the moon.
Game of Thrones Season 1, Episode 2

with her in the middle
of Trader Joe's.
The Big Bang Theory Season 5, Episode 14

Why did the TRADER from Qarth
tell you these stories?
Game of Thrones Season 1, Episode 2

a Dornish TRADER landed on Dragonstone.
Game of Thrones Season 5, Episode 4