What was the goal?
How was it executed?
What was the results/metrics/ROI?
How to Think about Social Media
You need to think about social media platforms as additional tools for the marketing toolbox. You still need a concise message. You still need to target a suitable audience with a relevant message. It's social so you have to interact, too. People do broadcast on twitter, but they let that be known from the beginning.
To start on any platform, Listen first. Learn best practices. Then Engage. Above all be authentic. Transparency counts. It's the Internet. Everything is permanent, searchable, and will be found out.
A couple of hints about LinkedIn from Suzanne: utilize the recommendations and questions/answers.
It is all about giving value back. (As Seth Godin says be generous). It is an avenue to becoming an expert, an authority.