You can save money on your dress, the reception food, music, photographer, flowers, and many more. But the most important part is to trim the guest list down. Especially you’re having a nice reception in a fancy place. Most places charge you by the head count. Adding one more guest adds more cost, not just the food, but rentals, and favors.
It’s nice to have everyone you can think of invited. But don’t invite people whom you haven’t spoke with in 6 years! Don’t feel pressure to ask every single girlfriend of yours to bring a date. Don’t ask everyone to bring their children. Because the caterer probably will charge the same for children.