“Take the bull by the horns” means “to deal with a problem in a direct and fearless way”. Example: After five years with the company, John decided to take the bull by the horns and ask his boss for a raise. Origin: Experts disagree about the exact.
"All bark and no bite" means "when someone threatens to do things that they are not really willing or able to do". Example: That new manager threatened to fire me again, but I know he won't do it. He's all bark and no bite.
“Shoot yourself in the foot” means “to do or say something that causes problems for you”. Example: When Michelle got drunk before her final exam, she shot herself in the foot. She failed the test! Learning English can be fun!