Of the productivity things I’ve tried in the last decade or more, keeping something by my keyboard to write on has been an unqualified win. I’ve used a yellow legal pad or notebook in the past, but the thing that works best has been a stack of index cards and a box to toss them in.
I use them to write something I need to do or look up, which can go into the box and get processed later if it’s not urgent. A card also works great for making a quick checklist. Even with simple tasks, there’s a certain number of braindead things I need to make sure I do, and the way my brain works, if I don’t have a list, the chances I forget one of those is very high.
Any work, but I like these Exacompta cards I got from a stationery store here in Portland.