One of the other things that I do, and recommend to everyone, is to maintain a journal to complement your productivity workflow. The reflective brain dump is a useful process as part of getting things done and I use my journal as a mechanism to reflect on the day and to identify things that I need to get done – and things I have achieved. This leads to clarity of mind, and a capture of actions that would otherwise slip through the cracks. I use Day One Classic (on my iOS devices) and Life Journal (on my Windows PC) to help me with this.
for the GTD process to work for me, a few things are essential:
The tool I use is ALWAYS available (online, offline, web, mobile)
It should allow me to create items for follow up from email (UPDATE: this is now a premium feature – which saddens me as this was a critical feature that was downgraded)
It should let me set up projects and break those down into tasks
It should have the ability to establish due dates and reminders
If necessary, it should let me collaborate with others
An ability to help me file and tag things and also prioritize tasks
Have a safe and reliable sync system across everywhere I used the tool