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.

Littlefinger looks at you
and sees a collection of PROFITABLE holes.
Game of Thrones Season 2, Episode 10

Look, hey, this is a squeaky-clean,
highly PROFITABLE...
Breaking Bad Season 3, Episode 9

...highly active, highly PROFITABLE
marketplace.
Breaking Bad Season 5, Episode 8