Blind leading the blind

Diamond in the rough

Face the music

Get out of the wrong side of bed

Hold your horses

Keep your chin up

Last but not least

Mad as a hatter

New kid on the block

On a wing and a prayer

All your eggs in one basket: you are risking everything at once, instead of trying to spread the risk.

Sow the seeds: start something that will have a much greater impact in the future.

Dime a dozen: it is extremely common, orten too common

Gild the lily: decorating something that is already ornate

I have fallen head over heels in love.

He is in hot water.

He is spread too thin.

He is beside his self.