I use digital notes, reminder checklists, and calendar with my partner, since those are shareable across our devices.

But, for work I use a small notebook where I write down every tasks to-do or completed, and the supporting tasks under that. I write the tasks in black, and X the check blocks I make for the tasks/subtasks in red. Any ticket numbers or additional notes (dates, etc) that come up are also written in red, so that they stand out more easily for review later.

For work related appointments or dates, I use outlook calendar.