Not what you might expect, but here goes
[The kind of system I'm about to describe may not work for you!]
I have my entire GTD system in the MemoPad. The MemoPad categories are Reference, >Projects, [8 total]@Contexts, #On Deck, and !Inspirations. (The punctuation ensures that I rotate through them in my preferred order as I hit the application button.)
Reference is pretty obvious: info that doesn't need archived paper and isn't actionable.
>Projects is my Someday/Maybe and my Projects inventory - I prepend a "+" to the active projects that haven't gotten an NA yet - these are commited, but not at their 'start date' yet. Everything else is a pool of possibilities, reviewed as desired, no less than weekly.
@[context] are my bins to hold projects that have at least an NA... since I also PigPog my projects, each "+" >Project entry that I decide to do something about gets an NA added as the new first line of the memo, and it goes in the proper context category. When the NA changes, so might the category, so I always have a real inventory of things I want to get to in each context.
#On Deck is my personal trick to keep visible just the stuff that I want 'up front and in my face'. I move entries from the @ bins in here when they are important enough that I want to see them before the rest of my NAs. (Since I keep my tickler items as @context items, too, this #On Deck list lets me put the active ticklers here, then drop them back in the @context bin when they're pending.)
!Inspiration is my way of reminding myself of all the helpful guidance I've collected along the way - helps me stay out of the self-deprecation and guilt and fear of failure and instead remember to take it a step at a time and just go for it...
This system evolved out of a few personal preferences; since I couldn't get the builtin apps to play nice together, or with others, I made a Memo-only system that lets me do the minimum necessary editing and changing to each project memo as it moves through the whole system in any required way.
[ "Your mileage WILL vary."
]
Howard