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.

...I will be less than USELESS.
The Big Bang Theory Season 1, Episode 6

And the draft's not for two months,
so this is USELESS.
Breaking Bad Season 4, Episode 3

At the rest of things in life
he was completely USELESS.
Money Heist Season 1, Episode 6

It is a big whoop. Made almost all the work
you've done completely USELESS.
The Big Bang Theory Season 2, Episode 11

So you're not so USELESS
after all.
Westworld Season 2, Episode 5