A hot potato

Speak of an issue (mostly current) which many people are talking about and which is usually disputed

A penny for your thoughts

A way of asking what someone is thinking

Actions speak louder than words

People's intentions can be judged better by what they do than what they say.

Add insult to injury

To further a loss with mockery or indignity; to worsen an unfavorable situation.

At the drop of a hat

Meaning: without any hesitation; instantly.

Back to the drawing board

When an attempt fails and it's time to start all over.

Ball is in your court

It is up to you to make the next decision or step

Barking up the wrong tree

Looking in the wrong place. Accusing the wrong person

Be glad to see the back of

Be happy when a person leaves.

Beat around the bush

Avoiding the main topic. Not speaking directly about the issue.

Best of both worlds

Meaning: All the advantages.

Best thing since sliced bread

A good invention or innovation. A good idea or plan.