Triathlon? Swimming, biking, and running.. ha ha.. oh you were serious? Is this you? Well, triathlons are not as hard as you may think. They are actually pretty simple. You just need to know a few basics.
Firstly, if you want to do a triathlon you need to commit. Register early fo that you will be positive that you want to go through with it, and also you may get a discount. Most triathlons are a bit pricey. Also, start training early, especially if it is your first, you don't want to get caught behind. Create a training plan and follow it strictly. Give yourself a couple of days off here and there, and train with swimming, biking, and running (since those are the events) and focus on your problem areas. About 3/4 of the way through your training, try to go to where the event is and simulate race day. Make sure you can go the distance and familiarize yourself with the course. Taper off your training as you near race day. The night before should be used to visualize your race and prepare you transition equipment. For more information on the transition check out this site.
On the morning of the race, plan to arrive early in order to have space and time to set up your transition area. Relax and stay calm at this point. All of your training will have prepared for this event, so don't sweat it. The first triathlon is always stressful, but the good thing is that if you don't like it, you don't have to do another one, and if you do like it, after this you're a pro!
Triathlon is a very challenging but simple sport. It's not for everyone and it takes a lot of endurance. Preparation is key. If you're interested.. Tri one!