Tip1: Enjoy it.
Tip 2: Ignore those riders who shoot off the front. Ignore those who hang back and then race past you. Ignore those who talk loudly at the start about how they’ve done this, that and the other, how they’re aiming for sub 3-hours, how they climbed everest yesterday and are swimming the amazon tomorrow. They’re only going to stop you fulfilling Tip #1.
Tip 3: It sounds like your goal is to finish (and that’s a superb goal, for anything, never mind your first major event). But don’t beat yourself up if you don’t, if that happens then see it as a stepping stone to the next event when you’ll get even closer. Enjoy the journey and celebrate the effort. And if you do finish, then party like it’s 1999 and celebrate the effort. So basically…Tip 1!