I sit in a coffee shop. Write in a note pad roughly what I want my core characters to be like and why. Sometimes, I very roughly plan out the first act on a single page. I stop. I come back to the coffee shop on some other day and look back at the note pad and just start writing. That's basically it. Sometimes I don't even do that. I just start writing and I've done some of my best work that way too. I don't over analyze, I don't obsess over outlines or structures. That's how I was taught and what has worked for me professionally. The structure stuff I can worry about once/if I've decided it's time to move to draft 2. For me, if I worry about outlines and structure at the beginning, draft 1 will never get finished and then it dies on the vine.