Email - I'm in email constantly, so it makes sense for email to be my primary tool.
Calendar - For meetings and time-specific tasks
Task Status Labels and bcc:Filters
Use a labeling system for task tracking in Gmail. Set up filters to auto-sort into the task labels,
Now - firstname.lastname@example.org - Items that need immediate action - this is the primary task list
Later - email@example.com - Items that are being deferred to the future - Set up calendar reminder to check every Monday morning.
Wait - firstname.lastname@example.org - Items that I am waiting for someone else to take action on. Check daily
1-1 - email@example.com - Items for discussion in 1-1 with manager
Skip inbox, archive, set label. Do not mark as read. Show label only if unread, except for Next Action, which should always display.
Add aliases to contact list to auto-populate. Name the contact "+na Next Action" for example.
On mobile, make sure Next Actions label is syncing (phone; tablet syncs all labels).
Task Implementation Checklist
Create address contacts for each address, put into a GTD contact group
Migrate existing task list into this system
Time-specific actions: Put on calendar, set reminder to send an email reminder
Consider day-specific labels (Mon, Tues, Weds, etc.) to assign tasks to specific days
Larger projects will each have their own tag label in addition to the above system.