I've just finished reading the first part of the David Allen book. Here's a very brief summary of what I understood as the basics of GTD:

Collect

Process

• Identify the incoming ‘stuff’.
• Ask yourself is it actionable YES or NO.
• If NO then categorize as follows: - it’s either trash bin it, or it will need action later incubate it, or it could be used for reference later.
• If YES then determine what the next action is resulting from this collected item based on the objective for the designated project that it belongs to:
• If it takes less than 2 mins then Do it Now
• If it takes longer can or should you delegate it?
• If not then defer it and add it to one of two lists :- do it as soon as I can, do it on a specified date.

Organize

From the above lists need to be maintained to successfully organize collected items:

• Trash – stuff that doesn’t concern you.
• Incubation – stuff that you cannot action but someday may be able to.
• Reference – stuff that you will need for reference at a later stage.
• List of projects – used to identify collected items into larger longer-term objectives. A project is defined as anything that requires more than one step.
• Project plans - tasks, schedules and milestones for these projects. This used to determine what the next action should be from a collected item.
• A calendar – for deferred tasks with a specific date on it.
• Reminder list – used for actionable items that can be done by you.
• Waiting list – used to remind to chase actions that have be delegated.

The calendar contains the following:

• Time tasks – i.e. appointments.
• Tasks that need to be done on a specific time/date.
• Date specific reference data. Information that you know you will need on a specific date.
• The ‘Next Action’ process is key to organizing. Based on the collected item you need to work out how that item affected the ‘Next Action’ for that project.
• Next Action lists can be categorized based on where you are. For example “calls to make” category can be used if you are near a phone and have some spare time.
• Categorize the ‘someday/maybe’ list based on classification. E.g. ‘CDs that I want’ or ‘Seminars to take’.
• Capture in a sentence how you define success for one of these commitments. Then list out the tasks of how to achieve it. Success is defined as being off your task list.

Review

• Check the calendar to items that were scheduled to happen that day.
• Check the Next Action list for items that need to be done next. This can be categorized on context (location) and project.
• Perform a weekly review that involves going though all the lists, dependencies etc. Check the process is working.

Do

There are four models listed to determine what tasks to do next:

•  The Four-Criteria Model: - select based on context (where you are), time available, energy available, priority.
• The Three-Fold Model: - do predefined work, work as it shows up, defining your work.
• The Six-Level Model : - Current Actions (stuff you have to do), current projects (projects flagged as high priority), areas of responsibility (projects via commitment), 1-2 year goals, 3-5 year goals, life goals.