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.

l'm a CASHIER at a car wash.
Breaking Bad Season 4, Episode 9

Hey, your CASHIER here
is quite the salesperson.
Breaking Bad Season 4, Episode 7

lt's the captain they want,
not some CASHIER at a car wash.
Breaking Bad Season 4, Episode 9

Guilty. Pay the CASHIER.
The Big Bang Theory Season 3, Episode 16

Pay the CASHIER.
The Big Bang Theory Season 3, Episode 16