Sending someone a save-the-date card who you later cut from the guest list.
You've got to be sure of who you're inviting to the wedding before you send out save-the-dates. Changing your mind later isn't polite. Don't be that bride!
Mailing them too far from or too close to the wedding date.
The ideal time to mail them is from four months to a year before the wedding and after you've booked a venue. If you're iffy on any details, hold off getting them.
Including too many details.
All that's needed are the couple's names, plus the wedding date and location; if you've got a wedding website URL, include that too. Keep it simple and sweet: No ceremony map or wedding timetable needed with this card—save them for the invite.
Missing a typo.
A misspelled word brings down the elegance of a piece of printed stationery. If proofreading isn't your thing, ask your English-lit major sister or your most detail-obsessed pal to read every word carefully or use this editor's trick: First, read top to bottom as usual then read bottom to top. It'll help you catch any errors when the words are out of context.
Ordering too many.
As with wedding invitations, you only need to send one save-the-date per family or household, not one per guest.
Forgetting to list a location.
Sure, the "when" is important on a save-the-date card but so is the "where." It doesn't help guests make plans if they only know you're getting married on June 18, but is it in Baltimore? Bali? Baton Rouge? Look at samples to figure out what to include on yours.
Asking for an RSVP.
You only put an RSVP on an invitation, not a notice, which is what a save-the-date is.
Not making them personal.
Why go with generic when you can have some fun with them? Use a goofy photo of the two of you or trendy color combos you love. Don't worry about the style matching your future wedding invitations. Save-the-dates can have a personality all their own!
Sending save-the-dates when you don't really need to.
If you're having a destination wedding or marrying during a holiday weekend (July 4, Thanksgiving) or peak travel time (a three-day weekend), send save-the-dates; everyone else, save your money for something you need, like a hot cocoa bar at the reception!
If you haven't figured out the whole "should I let single guests bring plus-ones or not" yet, don't write "Guest and plus-one" on the envelope. Better to delight guests later that they can bring a plus-one than disappoint them.