1. RSVP on Time--Wedding invitations are sent 6-8 weeks in advance. If you receive yours on the earlier side of this window, don't stash the RSVP card. If you do, you'll forget all about it. Your official deadline to get it in the mail is four weeks before the big day. Since wedding vendors will need a final head count from the happy couple 2-3 weeks in advance, there's no room for your RSVP to show up any closer than that to the wedding date.
2. Be an Informed Attendant--Don't accept a role in a wedding unless you're aware of your duties. In addition to gifts, attendants may need to contribute to the shower and help with the bachelor or bachelorette party. They're also responsible for their own attire, transportation, and often hotel rooms. The only one of these you may get to skip is hotel since traditional etiquette dictates that the bride and groom provide their attendants' lodgings. However, opinions still differ on this one so ask if you're unsure.
3. Know What's Mandatory--Of course your engaged friends would love if the entire wedding party attended the welcome party. But that's a lot to ask. The extra events you should attend if invited are those directly connected to the wedding itself: The rehearsal, rehearsal dinner if at all possible, and any pre-wedding hair-and-makeup sessions. Attendants should place a high importance on bachelor party and bridal shower as well, but they are not required to attend.
4. Never Add Your Own Plus One--Wedding invitations are addressed with a purpose and you're expected to read them as such. For example, "and Guest" means you're welcome to bring a companion whose name the bride and groom doesn't know. If only your name is written on the invitation? Only you are invited.
5. Don't Assume Kids Are Welcome--If children are invited, their names will be written on the invitation. The senders may list the children individually, or they simply write "The Smith Family" meaning the whole gang is invited. Also to keep in mind: Some couples decide they aren't able to entertain kids younger than a certain age, so they may list an older child's name and not another, indicating that the youngest isn't invited.
6. Arrive on Time--Making an entrance after the bride is not acceptable. Plan to be in your seat 30 minutes before official show time. If there is an unforeseen obstacle preventing you from getting to the ceremony on time -- heavy traffic, late babysitter, wardrobe malfunction -- never interrupt a ceremony service. Wait until the "I dos" are done and guests have left their seats to join the celebration.
7. Look the Part--Not every wedding dress code is as straightforward as black-tie or casual.
8. Be Seated Appropriately--It's still a general rule not to sit in the first couple rows of pews at a church ceremony or rows at an outdoor affair. Ushers should be briefed about the most important people on the guest list who'll be taking those spots, so if you aren't sure where to sit, look to them for guidance.
9. Respect the Bridal Suite--The room where the bride is getting ready before the ceremony is often off-limits. Most times there's a sign on the door requesting privacy, or an usher that asks you don't enter. Even if there's no clear sign not to enter, try to resist the urge to pop your head in as the bride busily prepares for her big entrance. You'll have chances to offer congratulations after the ceremony, plus she'll be able to give you her full attention.
10. Don't Play Paparazzi Unless Instructed--Your friends will get annoyed if photos of their big day leak at an alarming rate -- especially if they aren't the most flattering. And just as your phone tends to distract you throughout the day, it's going to distract the bride and groom if you have it out at the ceremony. Let the couple see your smiling face instead of the back of your iPhone, and keep it in your pocket until reception time unless instructed otherwise.
11. Rehearse Your Speech--Being called upon to say something witty, eloquent, touching, and profound before a room full of people can make even the most outgoing person tongue-tied. But when you really think about it, a good toast need only convey one story or message -- something simple and sincere. And there's no need to go on and on. The old adage applies: Keep it short and sweet.
12. Drink Responsibly--"Open bar" does not mean all-you-can drink. It means that the bride and groom have offered to pay for your cocktails for the evening. A wonderful way to show your gratitude is to indulge at an average pace so you can continue to celebrate the happy couple till the wee hours of the morning.
13. Treat the Venue Kindly--Once the DJ cranks up the music, it can be easy to forget you're partying on rented property. To score the space, the bride and groom took responsibility for keeping it intact by signing a contract and most likely putting down a deposit. To ensure they get their money back, your friends are looking to you to treat the location well.
14. Mail Your Gift--To prevent the bride and groom from having to haul dozens of boxes back to the newlywed suite, mail your gift prior to the wedding to their home. Check to see if the stores at which they registered give guests the option to ship gifts directly to an address.