Play with fire – to do something dangerous or risky.
Example: “You should study before exams, not party. Be careful, you’re playing with fire and you’ll fail!”
Throw caution to the wind – to become very careless.
Example: “I don’t throw caution to the wind, I always think my decisions through”
The coast is clear – there is no danger of being seen or of trouble happening.
Example: “Now that the killer has been arrested, the coast is clear and people can go out without fear”
Cry wolf – to ask for help when you do not need it, with the result that no one believes you when help is necessary.
Example: “She had cried wold about someone trying to rob her that nobody believed her in the end”
Look before you leap – Think carefully about what you are about to do before you do it.
Example: “Before you decide to just leave your job, look before you leap”