I don't know about you, but if I have a thought, I need to either write it down, or I grab my handy Sony microcassette recorder. I bought this several years ago. My husband teasingly says I'm talking to myself. Well, I am. As a writer, you need to talk to yourself. A lot. Even if it's on paper. You need to question "why does this character do this?" Or "Why does this character say this or that?" "What is their motivation?"
So, you see it all boils down to talking to yourself, because eventually you'll have the answer to those questions and you'll be talking to yourself.
I find a nice long walk in our park--by myself--the perfect place to get something hammered out. That's why the recorder is so handy. You walk and talk into it. People think you're on the cell phone, thus, you're not looked upon as nuts. Little do they know.
I'm working out a scene at a ball and trying to come up with dialogue. You'll fogive me if I don't go on about it. That would bore you--#1; And you wouldn't know what I'm talking about #2. But if you're a writer, you do understand what I'm saying.
Happy note taking!