So you don’t end up on someone’s bad list, here are some wedding guest dos and don’ts:

On the web

Unless the couple sets up a Twitter hash tag such as .Smithwedding where guests are encouraged to tweet updates about the day, forgo wedding play-by-plays. “It’s just another layer of etiquette that if not followed can really damage relationships,” Sharon Stimpfle, the Wedding Channel’s deputy site director, says of social networking and weddings. A friend posted an announcement about Stimpfle’s engagement before she had told her mother, so she’s sensitive to the issue.

Ask the couple whether their engagement is public before announcing it online, she says.

Ask permission to post any wedding-related photos or videos. Do not post any inappropriate photos, such as moments of debauchery.

Do not text during the ceremony, and turn your cell phone off.

Do not reveal who has or hasn’t been invited.

Do not RSVP via Facebook or Twitter unless the couple says it’s OK.

Resist complaining about the wedding in status up-dates that could possibly end up on the couple’s newsfeed.

The invitation

RSVP to weddings (and do it ASAP for a destination wedding). Vendors need accurate guest counts to arrange food and table settings.

Don’t bring a guest unless the invitation specifically says you may — that includes children. Take note of whose name is listed on the invitation’s interior envelope. Do not bring a date unless the card reads, for example, “Smith plus 1.” Do not bring children if they are not explicitly included on the invitation, i.e., “John Smith and family” or “The Smiths and Johnny and Susie.”