1. Don't use fast travel if you can help it. The point of a huge open world game is the opportunity to explore and have random encounters. Don't rob your self of these moments because you are in so much of a hurry to complete some quest that all you end up doing is fast traveling from one location to another. Take your time, see the sights and discover the world on your own.
2. Don't rush through quest lines. For example rather than rushing through all the Dark Brotherhood missions one after the other - instead do a mission, then go do something g else for awhile (work on the main quest, find a Daedric artifact, work for another guild, explore, etc) and then go back and advance the Dark Brotherood quest line when you are ready to move that plot along. This will help against feeling like those quest lines are rushed and that you go from nobody to guild master in a week.
Slow down and take your time with the game. You will enjoy it much more.
Any other hints on pacing that folks want to add?