These are some tips that I'm trying to follow after listening to "Getting things done" by David Allen. For more detailed description on why these things work I'd recommend listening to the tape or reading the book. If you're interested in the tape send me an email.

1. Do not create todo list but next action lists. The meaning of next action is the next physical action that needs to be done to complete a task. Therefore 'service the car' is not a valid next action but 'call garage for appointment' will be. Service a car is a project because it requires more than 1 action.
2. Write down all the next actions that need to be done. If you don't write them down your mind keeps trying to remind you to do things thus distracting you, so write things down.
3. Use your calendar as a sacred ground for keeping appointments. Make sure that each entry in the calendar can be completed on the date and time specified. This is generally useful for setting meetings, for task reminders use task in your PIM.
4. Keep the following lists:-

   Next action list

   Current next action list (Reviewed everyday)

   Unassigned action list

   Similar to next action but for task that are not going to be acted upon in the next few days. This is my customisation so that the next action list isn't too crowed to discourage me from starting anything. (Reviewed every 2/3 days)

   Someday maybe list

   List of future actions in the longer term (Reviewed weekly)

   Waiting on

   List of tasks that you are waiting for others. Date each item in this list. (Reviewed every 2/3 days).

   Projects List

   A list of projects that you are working on. A project is any task that requires more than 1 action. This list will act as a stake in the ground to remind you on your projects (Reviewed Weekly)

5. If any action takes less than 2 minutes to finish then complete it immediately when processing your in basket.
6. Reviewing a list is as important as the list itself.
7. Make it a habit to tag notes with a date.

E-mail processing scheme
Until I can find a cross platform feature rich PIM and e-mail reader I'm stuck with outlook as my email and PIM. This is the flag scheme I've adopted for e-mail organisation:-

At the moment I'm attaching time reminder to e-mails for deadlines; note that these reminders are not enlisted in the calendar.