bullet journal. I've played with different tools to help me keep organized and remember stuff, and this is my latest.
I went back to using paper over electronic tools for notes over a year ago based on research that showed you remembered things better when you took notes the old fashion way. Even then, I wasn't sure of the best approach. For a long time I was using standard legal pads, but I didn't want to take them with me when I traveled. I had a small organizer that allowed me to put paper in and out. I had tabs for different projects and clients but I found I was flipping pages to much.
I've adopted a way to combine the legal pads and my bullet journal. I still keep a legal pad at my desk and write down about everything. At the end of the day, I review my notes and copy everything over to my bullet journal. This serves as a review, makes sure I don't forget any action items, and gives me a chance to jot down some reflections at the end of the day.
I am using a Moleskin 5x8.5 dot grid soft cover notebook and a set of Sharpie fine point pens in 4 colors. I use different colors when I change subjects or otherwise want to highlight an idea. I have pages to capture books/movies/music I want to get, a page to capture things I'm grateful for, and a page where I have a year-long calendar.
We'll have to see how long I keep this up. I've got the book "The Doodle Revolution" sitting on my bookshelf, maybe I need to dust it off so I can add doodles to my journal.