Too many first timers spend a fortune on aero bars and fancy suits before they can even shift gears under load. It is a classic case of over-training the logistics while ignoring the actual basics of riding. A reliable bike that is actually ridden beats an exotic machine pampered in a garage every time, especially when you are just trying to survive your first event.
Focus on the transitions and getting comfortable with the gear you already own instead of falling down an equipment rabbit hole. Most of the fancy stuff is just noise when you are starting out.
What are the absolute must-practice skills for a beginner before they hit the start line? Also, what parts of the race day experience are actually safe to just wing on the fly?