I try to not think of brainstorming as a process, but instead just as "thinking random thoughts and writing them down." (Okay, technically that's a process, but a very rudimentary one.)
It usually ends up as a series of questions, which I then go back and write down potential answers for, but sometimes it's just getting thoughts I've already had down on paper, as they come back to me. And at least a few times when I've brainstormed, it ended up being a dialog between characters, or between myself and a character.
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Regards,
Eric Fretheim
Assistant Prep Leader, 2015 October NaNoWriMo Prep Challenge

"It is perfectly okay to write garbage-- as long as you edit brilliantly." ~C.J. Cherryh

“No, writing 50,000 words in a month is normal. You are not crazy. This is not insane.” ~Teri Brown