[colechristensen]

They can mean very similar things so that the question could be:

How to learn idioms when you have no one to teach you?

[spydum]

To which I think we land on the recommendation: seek good examples and mimic them. Trouble is finding them.

[LandR]

It is. I work in c# and if we take idiomatic to be how most devs write c#, then idiomatic c# is garbage.

[akulbe]

But the question still remains... how do you determine what "good examples" are?