Here's how to set up a global task list that works across the apps & services
In my biased opinion, most task organization systems are too rigid and fail to take the full advantage of the capabilities of the modern devices.
Specifically, the global search.
I use multiple programs that I generate tasks in - Onenote for meeting notes & project data organization, Xmind on the desktop / iThoughts on the iPad for brainstorming / plan development, email, Oulook / iPad master task list, etc. Until recently, I had to copy / export all tasks generated in these programs to my main task list or risk forgetting about them.
Well, recently I started doing a very simple thing... putting special characters in front of the tasks that I want to remember about. I use @@ for regular tasks and @@@ for the tasks that I need to work on today / next. I use this designation in every program that I work in at the moment (OneNote, iThoughts, email,Keep notes etc.) The reason I picked these particular characters is that they are rarely used in email (so few false finds on search) and are quickly accessible on the keyboard. (I used "!!!" at first but too many spam emails would show up in the search results).
I still maintain my master task list in my calendar program, mainly for the timed tasks that I want to appear on the calendar & assign alarms to + to have all my tasks in the desktop Outlook. But now I don't have to move all of my todos there. In my master task list, I use @@@ for the tasks that I plan on working today, and @@ for the tasks that I need to start paying attention to soon.
So now, when I run a "@@" search on the iPad, I get a global list of all of my todo items scattered across various programs, and if I run a search for "@@@" I get my Today's tasks. If I have a task that needs to show on Calendar in a particular date span, I export it to Reminders, but I don't have to worry about exporting all of them to Reminders anymore - they are right there at my fingertips no matter what program I have them in !