Basic GTD: You manage actions
"Things rarely get stuck because of lack of time. They get stuck because the doing of them has not been defined." ~ David Allen
You do not manage time. If you have five minutes available, no matter what you do, you will not end up with six.
You do not manage information overload. These days you cannot control the amount of information you receive.
You do not manage priorities. You have them.
The key to think more clearly, be more proactive, be more focused on your work and achieve better results with less effort, is to manage your actions. Many actions require little time in the right context, but to do them you need to identify them before.