The document outlines 3 mistakes companies commonly make on social media: 1) Trying to sell to new customers immediately without first being helpful, 2) Jumping into conversations without relevant information to contribute, and 3) Lacking an understanding of how different social media platforms are used and having different communication styles for each. The suggestions are to be helpful to customers, find conversations where valuable contributions can be made, and learn the unique rules and purposes of different social media channels.