The GTD Systematic Approach is only feasible if you can free your mind from having to remember every detail. GTD is system agnostic, so your preferred system could be paper-based, or choosing from a variety of computer-based tools. Here are several posts that demonstrate my experience working with GTD, what has worked for me, and what I sensed could be improved.
Transitioning to PocketInformant
NOTE: This post is actively being updated Importance of having a External Trusted System for GTD Evernote – Layout, Pros and Cons PocketInformant – Layout, Pros and Cons