I do a transition practice workout that consists of putting on my swim cap etc, start my watch, run to my bike, do my transition, ride around the block a couple of times at sprint speed, transtion to run and run around the block for about 5 min. I do this about 3 or 4 times over in one workout.

Think about how you can best lay out your clothes to minimize your transition time and DH and I really like elastic laces. It also helps to have a number belt.