I'll just echo the recommendation of
First things first by Steve Covey and also
The 7 Habits of Highly Effective People (same author). If you haven't read a book by Covey before I strongly recommend you read one of these!
I agree with Milo regarding urgence v importance; the biggest breakthrough for my time-management was really getting my head round Covey's time-management matrix (ie. the 4 quadrant model for Importance v Urgence). After a while I began to be able to instantly identity whether a task was a Quadrant 1 task or Quadrant 2 task etc. which gives you an excellent framework for decision making when planning how to spend your time most effectively.
Also simply by deciding which "Quadrant" a particular task falls into, by definition you are also thinking about what outcome that task relates to which can give you additional motivation to actually get it done!
I've found a diagram of the time-management matrix on
this page (scroll down a little to "Figure 1")