Packaging And Embellishments: If you're adding embellishments, or you're mailing more than just an invite plus an RSVP card (we opted to mail more info, because of the destination aspect), keep track of the weight of your invitation suite once it's all packed up. Depending on its size, you may be facing more postage fees than a simple stamp will cover. You can get a postage estimate using a kitchen scale and checking on the USPS website. Through the USPS website I also learned that square invites and envelopes cost more in postage, by a significant amount. It's not worth it.
RSVPS: Whether you choose to include a card for your guests to drop in the mail, a phone number to call, an email address to reply to, or a website to visit in order to collect your RSVPs, prepare yourself to have to hunt down more than a few people, regardless of your chosen method. We saved paper by only sending physical RSVP cards to our older guests (i.e., those who do not, and never will, own a computer or a smart phone) because we knew we'd have to chase down responses anyway. So we saved a little bit of money where we felt it might be thrown away otherwise. Here are a few more tips for collecting RSVPs.