In transition area:
Visualize where your transition station is as you set it up before the race, and then as you finish the bike, remind yourself of what your space looks like so you can run straight to it.
Set up your run shoes in the position that makes them easiest to slip on, maybe with powder in them and BodyGlide where your heel or arch may rub. (If you're going sockless, it helps sticky feet slip in more easily and decreases the chance of blisters).
On the run course:
Once you start running, remember this third segment is its own race, and enjoy it. Start out with a controlled but fast start, focusing mostly on your turnover rate and keeping your body position efficient. Run tall with shoulders open, arms relaxed, and at a subtle forward lean, thinking about your hip flexor speed instead of the power in your push-off.
Take water at the aid stations and thank the volunteers who give it to you. (They have a tough job!). Resist the urge to be overly aggressive at the start of the run - your body will thank you if you go for a negative split, even if you don't end up achieving one.
As you hit the halfway point, concentrate on increasing your effort and pushing hard to the finish. Consider picking some points on the course where you will intentionally change your pace or insert a surge to prove to yourself that can run even faster than you thought.
Have fun and enjoy the crowd's cheers as you come to the finish. Then congratulate yourself and your competitors on your hard work and a job well done!