10. Don’t RSVP ‘yes’ if there is a chance you won’t be able to make it to the wedding. If you’re uncertain or need more time, have an honest conversation with the couple. An empty ‘yes’ can cause major headcount headaches.
11. If you get a plus one, RSVP with the person’s name. That way the couple can include his or her name on the guest list, escort cards, and any other printed materials.
12. Always send your RSVP card back in a timely manner. If nothing else, make sure it’s sent by the RSVP date listed on the invitation.
13. If the invitation specially says no children allowed, don’t ask if you can bring your kids. Feel free to reach out to the couple about local babysitters or other childcare options. If it’s unclear if children are invited or not, you may need to politely ask.
14. If your invitation specifies the name of your plus one, and that person can’t make it, don’t bring a friend instead. Unless the bride or groom has given you the green light, the only people invited to the wedding are those addressed on the envelope.
15. If you don’t get a plus one, don’t bring a plus one. If you’re invitation doesn’t say ‘and Guest,’ then it’s safe to assume that you’ve been invited solo. You’re best off not asking the couple to make exceptions.
16. Arrive at the wedding events on time. It’s just common courtesy, right?
17. Don’t skip the ceremony. Sure, everyone’s excited to party. But your presence at the actual ‘I do’s’ is a must.
18. Turn the sound off on your phone during the wedding. While some couples may be okay with smartphone photos, turn off the flash sound, ringer, alarms, vibration, and any other disruptive alert.
19. Don’t wear a white dress (unless you’re asked to). Since white is reserved for the bride, steer clear of cream and ivory, too.
20. Don’t get too drunk. Make the most of the open bar, but know your limits. Don’t cause a scene at the wedding and be sure you can get yourself home safely at the end of the night.
This story originally appeared on Martha Stewart Weddings.