Be accustomed to group riding
In training be sure to get out in multiple group rides so you will be used to riding among other riders at high speeds and in tightly-packed groups. Chaingang training sessions with a local club will help you in this respect. Group riding with a club will have taught you about the benefits of drafting plus the cycling etiquette you’ll need to get around without incurring the wrath of other riders.
Be prepared for the course
Always familiarise yourself with the course. Often race organisers will share a map of the route well in advance so you’ll have had a chance to check out the ride and perhaps ride sections, if not all of it beforehand. If it’s going to be hilly course, then be prepared to climb and have a rough idea of the length of the climbs so you don’t expend all your energy part way up a climb. Take note of all the potential hazards and danger points on the course so you are well prepared.