play it by ear

(verb) to do something without planning

Example Sentences:

A: What are you going to do when you arrive to London?
B: I don’t have any plans, so I’m just going to play it by ear. When I get there I will make some decisions.

The workers decided that their project was too difficult to plan, so they played it by ear instead.

Instead of carefully planning my vacation, I’m planning on playing it by ear. It’s more exciting that way!