I help out with our beginner's in our tri club - I will tell you what I tell them. First off - congrats for taking the plunge. Go out and have fun - that is the main thing. Nerves are normal, everyone goes through this.
As to what to do/bring etc - here are things I try to get across.
Keep your transition area simple. Lay it out at home and try your changes. You don't need a lot, just your shoe layouts, and figure out how you want your bike laid out. I do helmet, glasses and sweatband on the bike, shoes on the towel. You may want to consider something to cover your gear in case it rains. Race belt is nice for your numbers, otherwise make sure your get it pinned properly before the race.
Pump - make sure your tires are properly inflated before the race.
Know how to change a tire - flats happen. Even though in a sprint it would be kiss of death if you were trying to place, if you are just trying to finish you should be ready to deal with this.
Nutrition - you don't need much for a sprint - one bottle on the bike should do. You can probably get by with what is on the aid stations on the run. Maybe tuck a gel in if you think you will really need it.
Finally - have you had any open water/wetsuit time yet? You really need to get some in before your first race. Open water is different than pool, you should be comfortable sighting and get used to not having the black line. Also, you relative sense of motion is different in open water - you often think you are going nowhere since lines of site are so much longer. Don't freak out when you see the course laid out - it will look huge. You can do the distance. If it is a wetsuit race, get used to swimming in it before you go - it does change your feel in the water. Finally on the swim, consider where to seed yourself in the wave. If you are a fish, you may want to be at the front, if not, further back and even to the outside so you don't get hammered would be a good idea. All in all, you do not want your first open water experience to be at your race.
I think you have a good approach, every race is a good learning experience. I always find something new to screw up in each race I do.
If you have any more specific questions, fire away.
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