“Fight an uphill battle”

“An old hand”

A person with a lot of experience in something.

“Curiosity killed the cat”

Being too curious can cause trouble.

“Cry over spilled milk”

To be upset about something that cannot be changed.

“Don’t judge a book by its cover”

Don’t judge by appearance.

“Fight fire with fire”

To use the same methods as your opponent.

“Get cold feet”

To become nervous and change your mind.

“Go the extra mile”

To make extra effort.

“Give someone the cold shoulder”

To ignore someone deliberately.