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.

Wagner hasn't had to be
really STELLAR tonight.
Breaking Bad Season 5, Episode 15

- ...the STELLAR evolution research team.
- You're kidding. That's fantastic.
The Big Bang Theory Season 3, Episode 4