Think Before You Join a Social Site

The most important thing is never mentioned - never start a NEW method of communication, new features, new expanded ANYTHING unless you have already allocated TIME to MAINTAIN them.
Using Twitter? You BETTER ensure that you have 10 minutes a day to post something  - AND - allocate time to READ what comes to you and stay involved - or else people will ignore your tweets.

You join into 4 or 5 social sites you have just dedicated an HOUR A DAY to them regardless of what is going on. Unless you ration yourself, you will soon find yourself hopelessly overbooked during a day and falling behind.