You might be interested in the book Getting Things Done. It was written before smartphones and cloud syncing calendars but it can easily be adapted to To-Do lists and managing your life in the modern age.

A basic summary is thus: Every action you need to do but haven't yet done is an open loop in your mind. You have to keep thinking about it until you do it, and close the loop. However, lots of things can't be done except at specific times and places. You can maintain seperate to-do lists for things that can be done anywhere (Call a friend to schedule a movie, tie your shoe, etc.), and things that need you to be at your desk, at work, or at a grocery store. Storing all the myriad things that you need to do in life in your head is stressful and difficult to successfully accomplish. If you offload this information to contextual to-do lists, you can forget about the open loop and rely on your general system to remind you if it only if you can actually do something about it. This allows you focus on things you're doing in the moment, without worrying that you're forgetting a bunch of things you still need to do.