On my phone, I've been using Wunderlist for the past couple weeks. It's pretty good. Folders for tasks, reminders, cross-platform integration. I used Any.do for a while, but for some unknown reason, there seems to be no way to mark a task as completed without setting a due date. It was amazing as a management app though, as it would also filter phone calls, and tasks could be linked to contactsor store purchases. I liked that aspect of it a ton, but I really needed to be able to cross things off, so I switched to Wunderlist. I also use a pocket notebook (often homemade ones). That is mostly for if I need to plan out a single day where I plan to do several things that have been on my plate for a while, or when I don't want the distraction of my phone (often for writing tasks). I just use a bullet list beneath the date, and then cross things off as they go.