If search engines and e-mail are two cornerstones of web marketing these days, social media is the third. It’s no longer a question of whether to use social media, but rather which are best suited to your audience and to you. This answer is designed to give you a very brief overview of what’s available and how the tools can help you.
72. Which social media will you use to promote yourself?
From Chapter 8 of 100 Questions To Ask Before Building A Website