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.

He's WILDLY unstable.
Westworld Season 2, Episode 3

(Sheldon whooping WILDLY)
The Big Bang Theory Season 5, Episode 21

I'm WILDLY expensive.
Game of Thrones Season 4, Episode 1

Oh, that was
WILDLY carcinogenic.
The Big Bang Theory Season 5, Episode 15

-He's WILDLY unstable...
Westworld Season 2, Episode 5