Step #1, you need to get your name out there in the social media circles. If you don't have a facebook profile, make one. Once you have a profile, make a page. The page is where the magic will happen. Make sure you tell your friends early and often to 'like' your page. This is where I (for lack of a better suggestion) will keep a tally of my following as we go. The number of 'likes' will correspond to the number of people who are following my progress and therefore (hopefully and in most cases) buy my book when it is released.
The more eye catching your facebook page, the better. There are tons of websites out there that tell you how to do it yourself and also tons of websites that want to do it for you(for a fee). You can also specify where you want new visitors to go when they arrive. This is called the landing page. This is your chance to get them hooked. I am currently using Pagemodo, which is free and seems to work easily. The interface is user friendly.
Now, you want to drive as much traffic to your page as possible. The first, easiest and cheapest way is to post often on your profile page and entice your friends to take a look at your author page. Make sure to tell them to 'like' it. If you have friends with websites, ask them if they'll link your page in their site. The more external links the better. Here is my link, which will hopefully drive some of you over to my page. Remind your friends that your author page is out there and needs your help! ...I better do this now!
Unfortunately, I'm running out of time right now. I'd still like to cover driving more traffic to your page and driving the right kind of traffic to your page...until then.
J. R. Wagner