It's not rocket science
It's not complicated
The ball is in your court
It's your decision
On thin ice
A warning; if you make another mistake, there will be trouble.
cost an arm and a leg
very expensive
There's no such thing as a free lunch
Nothing is entirely free
Throw caution to the wind
Take a risk
The best thing since sliced bread
A really good invention
Give someone the benefit of the doubt
Trust what someone says
Hang in there
Don't give up
On the ball
Doing a good job
Put something on ice
Put a project on hold
There are other fish in the sea
Other opportunities will come along
Add insult to injury
To make a bad situation worse
A picture is worth 1000 words
Better to show than tell
Hit the sack
Go to bed
hold your horses
wait a moment
Pull someone's leg
To joke with someone
Once in a blue moon
Rarely
Spill the beans
Give away a secret; to gossip
break a leg
good luck
Saving for a rainy day
Putting money away for the future, or possible emergencies
Actions speak louder than words
Believe what people do and not what they say
Wrap your head around something
To understand a complicated idea, situation or process
Give someone the cold shoulder
Ignore someone
Look before you leap
Take only calculated risks
Let the cat out of the bag
Give away a secret
Take it with a grain of salt
Don’t take it too seriously; don't believe everything you are told
Go back to the drawing board
Start again from the beginning
Miss the boat
To miss an opportunity; to lose out on something
You can't judge a book by its cover
This person or thing may look bad, but it's good inside
A blessing in disguise
a good thing that seemed bad at first
call it a day
stop working on something