The BigLig Thinks

So, what are these tools you need?

GTD is about workflow. You collect "stuff" - ideas, instructions, messages, thoughts into collection boxes. Then, every so often, you go through the stuff and process each piece.
First you decide if it is actionable. If not, you junk it, file it for reference, or maybe put it on a "nice to have" list to ponder in quiet moments.
If so, you either do it there and then, or delegate it, or defer it to later.
There are two sorts fo deferment; sometimes you have to defer it to a particular time in the future, otherwise you defer it to when you next have time.
This is a terribly short precis, read the book or visit 43 Folders for a proper description.
Anyhow, from all this you need three tools:
A collection tool that you use to gather stuff together
A list tool that you use to make lists of the action itmes you will do when you next have time.
A calendar tool you use to record things you are defering to a particular time in the future. The Calendar ideally links to the collection tool so that stuff magically gets collected when the time comes due.