Dress, hydrate, and protect yourself from the sun appropriately.
The following are essentials:
*Race apparel (jersey, shorts/bibs, helmet)
*Change of clothes for after race
*Shoes (clipless or non-clipless)
*Eye protection / sunglasses
*Proof of race entry
*Hydration and nutrition (before, during, and after race)
*Tool kit, including spare part essentials such as tubes, and a pump
*Plastic bags for wet clothing, and towels to dry off with or change of clothes
Make sure your equipment is up to the race or ride is a very important and often one of the more overlooked areas for new riders. The last thing you want is to have a mechanical issue during the event due to something that could have been easily spotted and fixed. It is a good idea to have a bike shop or mechanic to carry out a check on your bike at least a week before the event. Be sure to check everything from your helmet to the cleats on your shoes to ensure everything is in good condition.