I'd say that the very name of the GTD system, Getting Things Done gives a big hint as to what's the "right" system. It's whatever system lets you Get Things Don

I'd say that the very name of the GTD system, Getting Things Done gives a big hint as to what's the "right" system. It's whatever system lets you Get Things Done. It doesn't have to be some fancy complicated system. It doesn't have to require any software or notes. Whatever works for you. Try several things, see what sticks and is effective for you. Personally I've discovered that a combination of project TODO files, and general TODO files, plus iCal events, plus my brain, is an effective combo for me.