David Allen is a master guru of productivity. In his book , he summarizes best-practice behaviors for personal task management as:
Get everything out of your head. Make decisions about actions required on stuff when it shows up—not when it blows up. Organize reminders of your projects and the next actions on them in appropriate categories. Keep your system current, complete, and reviewed sufficiently to trust your intuitive choices about what you’re doing (and not doing) at any time.
Further on, distills this advice into the following single sentence of wisdom:
Focus on positive outcomes and continually take the next action on the most important thing.
Simple advice, and probably the single greatest pearl of truth written on how to be productive.