I guess it is Extreme Programming Day here at Making It Stick.
Kent Beck writes about planning...
We deliver functionality but we build relationships. Planning is more about building relationships than it is about delivering functionality.I teach a "whole team" Agile/XP course a half dozen times a year. I emphasize values a much as practices. Communication is the value at the top of the list. We also spend a significant bit of time discussing how to adopt XP. My first (and often repeated) message is, if you can only take one thing out of this course then take the benefits of "clear communication with your whole team" into whatever practices you do choose.
Not only is communication the most important value it is also the easiest thing to adopt as an individual under any circumstances. Build relationships.