Reading the field

I was reading an article about finance that was advising to be good at reading instructions and reading the field. It quoted Warren Buffet as saying, "It's better to be medium-good in a great field than great in a medium field." In the sense of the article it was saying that you needed to know where money can be made (ie read the field) and go there.

I'm sure this applies to many more things in life as well. I can't quite articulate how at this point, so I'll just keep this quote in my back pocket for while.