The Autofocus Time Management System was developed by Mark Forster as a reaction against the common time management advice that tasks should be prioritized on one’s opinion of their importance. He found personal prioritization unhelpful at best and harmful at worst.
Forster’s Get Everything Done website explains the planning technique and how to implement it. He provides a free, downloadable PDF version.
Book launch expert Tim Grahl recommends this, and it resonates with the way I work when I’m working well.