Unfortunately, there have been fewer experimental studies on effective productivity and time management methods than there have been on effective study methods. For an overview of scientific opinion on productivity, I recommend pages 121-126 of Psychology Applied to Modern Life. According to those pages, common advice from professionals includes:
- Doing the right tasks is more important than doing your tasks efficiently. In fact, too much concern for efficiency is a leading cause of procrastination. Say “no” more often, and use your time for tasks that really matter.
- Delegate responsibility as often as possible. Throw away unimportant tasks and items.
- Keep a record of your time use. (Quantified Self can help.)
- Write down your goals. Break them down into smaller goals, and break these into manageable tasks. Schedule these tasks into your calendar.
- Process notes and emails only once. Tackle one task at a time, and group similar tasks together.
- Make use of your downtime (plane rides, bus rides, doctor's office waitings). These days, many of your tasks can be completed on your smartphone.