> However, retaining one to advise you on how to navigate the process, how to phrase your arguments, how to communicate with the opposing party, etc.

How, exactly does one "retain" a lawyer?

Is that a formal, monthly-fee kind of thing, for the ability to call them up for questions and advice?

Or is it more like an informal, having done business in the past, maybe for a larger lawsuit, getting to be friendly, and knowing a guy who knows a guy, sort of thing?