I've talked a lot about the danger of using idioms.
Remember that if you get even the slightest thing wrong, it has a comical effect.
Today on Twitter, the (possible) future Prime Minister tweeted:
"I'll hit the ground" (meaning "to fall flat on your face after a disaster")
She should have said: "I'll hit the ground RUNNING"
(Meaning: "to immediately work hard and successfully at a new activity")
She immediately deleted the tweet, as she was "widely ridiculed".
(Lots of good vocab for mistakes - e.g. a 'gaffe', a 'blunder')