i know some ^^
A hot potato : Speak of an issue which many people are talking about and which is usually disputed.
A Penny for you thoughts : A way of asking what someones is thinking.
Actions speak louder than voices : People intentions can be judged better by what they do than what the say.
Breaking up to 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.
Ball is in your court : it's up to you to make the next decision or step.
Can't judge a book by its cover : can't judge something primarily on appearance.
Cry over spilt milk : when you complain about a loss from the past .
Cut corners : when something is done badly to save money.
Costs an arm and a leg : this used when something is very expensive.
Don't count your chickens before the eggs have hatched : this used to express , don't make plans for something that might not happen
Every cloud has a silver lining : Be optimistic even difficult times will lead to better days.
Feel a bit under the weather : feeling slightly ill
Give the benefit of the doubt :believe someone's statement without proof.
hit the sack/sheets/hay : to go to bed
it takes two tango : actions or communications need more than one person.
jump on the bandwagon : join a popular activity or trend.
keep something at bay : keep something away.
let sleeping dogs lie : don't disturb a situation as it is , since it would result n trouble or complications.
make a long story short : come to the point , leave out details .
Not playing with a full deck : someone who lacks intelligence .
on the ball : when someone understands the situation well .
piece of cake : a job or task or other activity that is easy or simple.
speak to the devil : this expression is used when the person you have just been talking about arrives.
take with a grain salt : it means not to take what someones says too seriously .
wouldn't be caught dead : would never like to do something.
your guess is as good as mine : to have an idea , don't know the answer to a question.
there's also more , but it's okay. hope you got enough ^^
There are several complete dictionaries full of American idioms. (Search google for ¨American idioms book¨ and you will see.) Some are more common in certain regions of the U.S. I do not think any of us Americans can easily tell you which few might be the very most common. If you give us some examples, we might be able to tell you which are common in our area and which we hardly have ever heard.
I do not think you realized what a hard question you asked-- there are just way too many of them. If someone asked you to tell them the most common Portuguese idioms would you be able to do it?