Moriatesg has it right on, the biggest things is training and racing to figure out the pace that works for you. Also incorporating some bricks where you bike and run could help give you a better sense as to what works. In the sprint distance it shouldn’t be too difficult to include some full distance bricks into your training routine.
Tools like heart rate monitors and power meters are great for pacing if you decide to invest more time and money into the sport (I swear by my Power Meter and Heart Rate Monitor). But World Champ Chrissie Wellington uses neither so its like like they are *must haves* to sort out your performance, but she truly is an exception.
Just keep training and racing and listen to your body and during/after your workouts spend a few minutes thinking about what worked and what didn’t with your approach.