Following other people on Twitter will frequently get them to follow you in return. But it's not quite that easy. You have to engage people and participate in their discussions. Do NOT push your site or product... Maybe 1 in 100 or so tweets should be about your site. The other 99 of 100 tweets should simply be you interacting with others, having fun, cutting up, sharing cool or funny things you've found out about... basically building relationships. As far as Facebook goes, it's a little different beast. IMO not all websites are conducive to Facebook promotion. If your site is about events of some type or someone famous, for example, then this is a great opportunity to use FB. You can announce upcoming events or appearances on a Facebook page. You can create a "page" for your business/website. Not a personal page, but a "page" for your site that people can become a "fan" of. Target your friends to become fans first. They are most likely to become a fan if they know it's your site. Once you have friends as fans, their friends will be prompted to become a fan automically by FB in the same portion of their home page where FB suggests that they add friends of friends as a friend of their own. In the case of both Twitter and Facebook, the key is to NOT become annoying and piss people off. No one wants you spamming their FB or Twitter feed with self promoting propaganda. Be selective about what you post on Facebook. Participate, engage, but don't annoy.