Douglas White on Social Media Today published a great study on engagement on twitter and online forums.
What appears to be working extremely was:
- Threads were created as questions so as to elicit a response
- Forum entries were written in a conversational manner. Not all entries contained brand messages
- Replies to comments from readers were followed up and brand messages were included when appropriate
- The brand message was included at least once in all conversations
I strongly suggest you read the rest of the article, impressive numbers!