watch out for sth / Beware of sth 当心某事

watch out for sb 当心某人

be careful with sth 小心某物

Look out/Watch out/Careful/Be careful/Beware/Mind

Watch out for the stairs, They are steep.

You have to watch out for insincere people.

insincere（adj.）:虚伪的,不诚恳的

Beware of greeks bearing gifts

Please mind the gap between the train and the platform.

I'd be careful with that faucet, the water comes out very hot because of the fracking.

This way, watch your step(mind your step)

Be careful, it's very slippery.