Etiquette for writing social documents

• RSVP: If someone sends you an invitation that says “RSVP” (a French expression meaning “please respond”), you should reply to this individual as soon as possible. Not responding or doing so late is both rude and inconsiderate.
• Sending invitations: How far in advance you send out invitations depends on the event. For an informal lunch or dinner, you can send an invitation—or merely email or call someone—anywhere from a few days to weeks ahead of time. On the other hand, if you’re having a holiday or Christmas party, you’d send your invitation about a month in advance.
• Thank-you notes: If someone sends or gives you a gift, takes you to lunch or dinner, or otherwise helps you, you should send a thank-you note as soon as possible. Generally, these days, it’s acceptable to email your note. But, if you’re sending your thank-you to an older person, you may want to write a handwritten note.
• Congratulatory notes: You can buy and send a card in which you write a personal note, or you can write a handwritten note or letter. You’d send this type of note to someone who gets a new job or promotion, a recent university graduate, a recently-married couple, or the parents of a new baby.
• Condolence notes: You can buy and send a condolence card in which you write a personal note, or you can write a handwritten note or letter. You’d send this type of note to a coworker’s or friend’s family on the occasion of his or her death, a neighbor’s family, or other person who’s experienced such a loss.
• Addressing others (in writing): When contacting a man, “Mr.” is fine. When writing a woman, “Ms.” is usually acceptable—unless you know that this woman prefers “Miss” or “Mrs.”.