Back to the drawing board
To start over; to plan another idea from scratch.
A long shot
Something unlikely to happen with very little chance of success.
Beat around the bush
to delay or avoid talking about something difficult or unpleasant
To learn the ropes
To learn the basics of a profession
Bite the bullet
to accept a negative situation in order to proceed
By the book
To do things strictly by the rules
Cut me some slack
to treat someone in a less critical way
Dime a dozen
Something that is very common