The guide provides advice on posting photographs, removing someone as a friend and "poking".
Debrett's said that users should never post a profile picture they would not want to see in their local newspaper and should consider friends' feelings before posting pictures.
The etiquette expert also said that you don't have to make friends with people you don't know and that it was always necessary to wait 24 hours to "gather your thoughts" before accepting or removing a friend.
Debrett's also points out that birthdays, engagements and weddings are not "virtual" events so you should send cards or call your friends when there is important news.
The rules follow research by telecoms giant Orange, which found that almost two thirds of people are frustrated and confused by social situations presented by social networking sites such as , and .
More than a quarter said that they were uncertain how to respond to unwelcome "pokes" or messages. Confusion also arose over responding to former partners once in a new relationship.
Annoying habits named by users included allowing social networking to become more important than real world events and posting embarrassing photos without permission.
Jo Bryant, an etiquette adviser for Debrett's, said: "The trend for social networking has made new demands on traditional etiquette. Play it safe, and always employ your usual good manners when online, treating other with kindness and respect.
"Remember social networking is meant to complement and enhance your existing social life, not complicate it."
Debrett's has published a range of modern social etiquette guides such as Debrett's Wedding Guide and Debrett's Correct Form. Still available are Debrett's classic editions such as Debrett's Peerage and Baronetage and Debrett's People of Today.