Don't spam! Don't block! Most message boards don't allow flagrant advertising, but permit sigtags. Until publishing, make sure you read all laws thoroughly.

Message boards are an excellent way to develop your reputation and become an expert. Contacts on boards can also launch corporate and personal contacts.

Join in the debates! You would definitely like to take part and be aware of the discussions.

There are messaging boards that enable any kind of publicity, but they're not very helpful to network or learn something.