For a successful careerSimple targets work best, for example, if you're measuring interactivity, count number of Twitter @ replies or followers. And definitely count the number of hits on your web properties originating from Twitter, Google+ or wherever. If you insist on having fancy tools, there are lots available, although I'm slightly dubious of the value of tools such as SocialBro, and outraged at the spurious influence claims made by Klout. So keep it simple and measure your impact by setting clear targets to aim for.
Find something to measure
And measure the f**k out of it.
For more in the same vein, be sure to follow the live video stream from Martin Weller's keynote talk at #dr12vitae.