When playing real (i.e., slow time control) games, I have two time-management goals that are often in conflict. One, I try to use up all the time on my clock. That is, I don't want to rush moves. Two, I don't want to play so slowly that my flag falls.
One thing that helps me avoid a rushed endgame is to divide the total time T by three, and to plan on having a minimum of 12 moves made with 2/3T on the clock, and 24 moves by 1/3 T (so in a 60 minute game, I want 40 minutes left at move 12 and 20 minutes left at move 24). This simple algorithm has helped me a lot, but it isn't perfect. For instance, the above assumes a game will have about 36 moves, but this is often wrong and I end up in trouble in the endgame. I am so bad in the endgame I should give myself more time to think then. Also, the above rule is not etched in stone: a third of the clock is too much for the first 12 moves in familiar openings, so I often take less time for the first 12 moves.
Heisman suggests taking a deep think at certain critical junctures such as the first opening move that is out of your book, complicated tactically rich positions, and when you are making a positional committment that will have long-term positional consequences (e.g., a pawn break).
Anyone out there have any useful time management tips?