A clunky registration form is the fastest way to lose someone who was already planning to come. CiviCRM's Event module can do a lot — multiple ticket types, waitlists, automatic confirmation emails — but it's easy to build a form that asks for more than it needs to.

Keep the required fields to the minimum you'll actually use. If you're not going to look at someone's dietary requirements until the week of the event, don't make it a blocker on the form itself. Test the whole flow yourself before you send it out, including what the confirmation email actually looks like — it's often the thing people reread on the day.

And if it's a paid event, double check your payment processor is definitely connected before you publicise it. That one's caught a few of our clients out on launch day.