To be different from the rest; to do things in your own way.
"Everyone except Sarah went to the bar. She marches to the beat of a different drum."
When you blow your own trumpet you boast about your achievements or talents; you are not modest.
"I don't want to blow my own trumpet, but I got the highest score on the test."
To change your opinion completely.
"Peter said he didn't want to go to the party, but he soon changed his tune when he found out that Sarah was going."
When something is 'going for a song', it is very cheap.
"They're closing the shop at the end of the month so all their products are going for a song."
Something that you are very pleased to hear is described as music to your ears.
"The sound of my daughter's laugh is music to my ears."
To be less important or in a weaker position than someone else.
"I'm tired of playing second fiddle to James. I'm going to find another job at another company."
