Studying, exploring and getting to know one of the applications I am responsible for and taking notes for me in the process.
Theory and Practice
As I explore and learn about the application or technology it's best for me to immediately log in to the server(s) and traverse the filesystem up and down, practically hands-on checking out files and structures as many as possible - instead of just listening to or reading about the application and how it works and how it is structured/deployed on the OS/server.
Being Hands On as Fastest Way of Integration
Best way to integrate information and build skill in any area is immediate or asap HANDS-ON experience with it!