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.

For example, I noticed
you PURCHASE your tampons...
The Big Bang Theory Season 1, Episode 4

did you make a PURCHASE?
The Big Bang Theory Season 5, Episode 13

to PURCHASE the car wash,
that protects the innocents
Breaking Bad Season 4, Episode 3

I would like to PURCHASE
this comic book, please.
The Big Bang Theory Season 7, Episode 24

at a retail establishment,
to make a small PURCHASE.
The Big Bang Theory Season 5, Episode 13