A blessing in disguise
A good thing that seemed bad at first
A penny for your thoughts
Tell me what you're thinking
Break the ice
Make people feel more comfortable
It's raining cats and dogs
It's raining hard
Like riding a bicycle
Something you never forget how to do
Better late than never
Better to arrive (or to do something) late than not to come (or do) at all
Bite off more than you can chew
Take on a project that you cannot finish
Once in a blue moon
Rarely
Burn bridges
Destroy relationships
It's not rocket science
It's not complicated
Break a leg
Good luck
Add insult to injury
To make a bad situation worse
Go on a wild goose chase
To do something pointless
The devil is in the details
It looks good from a distance, but when you look closer, there are problems
Let someone off the hook
To not hold someone responsible for something
Get out of hand
Get out of control
Every cloud has a silver lining
Good things come after bad things
Let the cat out of the bag
Give away a secret
Familiarity breeds contempt
The better you know someone the less you like them
Beat around the bush
Avoid saying what you mean, usually because it is uncomfortable
Hang in there
Don't give up/be patient
By the skin of your teeth
Just barely
He has bigger fish to fry
He has bigger things to take care of than what we are talking about now
A stitch in time saves nine
Fix the problem now because it will get worse later
That's the last straw
My patience has run out