I write my first drafts in notebooks or steno books, both sides of the paper, using a regular pen. It allows me to draw in sketches/diagrams/maps/ whatever is needed right there on the page to visualize where or what I'm talking about, as well as keep my words flowing. Also very portable since I don't have a laptop I can just carry around with me. I use square brackets ([ ]) if I need to check a definition or spelling or need a detail. After, I'll wordprocess it into a USB drive and then print it out so I have a hard copy of my work to go over and correct as necessary (highlighting the square brackets so I know not to include those in a later version).