In the previous post in the series I went over what to say, or possibly what not to say. Now that you've gotten started, many ask the question of how do I measure the results of my efforts in social media. The easy answer is it is much harder to measure it quantitatively than say the impact of a website (how many hits/unique visitors/length of stay on page/etc). You won't be able to measure impact immediately no matter what. It takes some time to build up that trust that is so necessary and to make all the connections that will make your social media foray a big hit.
So what can you do. There are metrics you can use. There are things like twitanalyzer, twitttergrader, twittercounter, mrtweet, and others that measure various different things on a twitter profile. A great tool I highly suggest using is bit.ly. Bitly is a URL shortener, but it is much, much more. If you register for an account at bit.ly, all your shortened URLs can be tracked and you can see how many people clicked on them, when, and from where (approx). This is a great tool that can be integrated into other twitter tools to automatically shorten and track your URLs. A word of warning: even if you do this well, it will take time to build up the amount of click backs (clicks on your URLs) that you would like to see.
I have a list of sites and articles on social media metrics on my delicious account at: social media metrics.
Series of 5: Parts 1, 2, 3, 4