play by ear
play it by ear
play something by ear

After that, we'll pretty much be playing it by ear.

But right now he'd have to play it by ear.

So we'll play it by ear until we know the set up.

He turned to face his father, to play it by ear.

Give her an hour, play it by ear if she left.

From there on in, they would have to play it by ear.

I'd have to play it by ear when I got there.

"Is there a better time than another to approach, or should we just play that by ear?"

We'll just have to play it by ear for the moment.

I'll let him wear himself down a little, and then play it by ear.