Whenever I work I am always jotting down things on pieces of plain paper next to me - this could be things to do, ideas, random thoughts, planning for meetings, etc.. Every week or so I do a cull of this stack of paper and then start on a new piece of paper.
Recently I bought a small whiteboard for my daughter which she uses to plan her schoolwork. It seemed to work very well for her so I thought I would give it a try. I bought an A4 magnetic whiteboard. For me the magnetic part wasn’t important, it was more about the thin form factor so I could sit it on the desk next to me.
So far it is working really well. I find myself writing down more than I did before and I am naturally using it for planning and capturing thoughts. If I need to save something for future use I just take a photo of it and optionally transpose it to a different medium later.
My wife used to plaster the kitchen top with numerous random post it notes with her to do list. Apparently this sort of worked for her but was not great for the rest of us. She is currently transitioning to using an A5 whiteboard and initial results look good.