to play it by ear = to improvise rather than plan

“My friends and I hadn’t booked any part of our trip, but ‘played it by ear’, queuing in sweaty ticket office lines and taking it in turns to fetch water …”

to hit the book = to study

It’s been about 30 years since I hit the books on this stuff, so can not longer give you the math without looking it up.

to take the rough with the smooth = to accept the unpleasant parts of a situation as well as the pleasant parts

1. Who do you get on with like a house on fire?
2. Would you feel homesick if you had to live abroad for about a year?
3. Are you one to tell people a few home truths if you are not happy with their attitude?
   

the ball is in your court = it is your turn to take action / your responsibility

I realised the ball was in my court. No one else would have the same opportunity.

Can you answer these questions? All of them contain expressions connected with clothes.

mud sticks = said to mean that people are likely to believe something bad that is said about someone, even if it is not true

Mud sticks, however unjust and fourth-hand the accusation, however misguided your accuser and however hard you fight to clear your name.