There are many forms of promotion. The easiest is a paid spot on a review site or blog. And those are great. But they shouldn't be your only shot at promo. They should be the icing on the cake.
Now, I'm far from an expert, but I've found that, for me, the best promotion I can give my work is not to promote the latest book, but promote myself. No, I don’t mean by posting my logo everywhere, or simply maintaining my website, although that is extremely important. I mean, create an online presence. Facebook, twitter, blogs… all those help with this presence, but even that is not enough.
You have to be memorable. Whether you're funny, silly, seriously sexy, or just all out goofy, get readers to notice and like you. Your excerpts need to draw the readers in, but more often than not, if they like YOU, they will buy the book your selling. They'll buy it because they like you.
Do something unheard of. Have a chat and… gasp… don't talk about yourself. Talk about a movie you've seen that you really liked, or a band you love to listen to. How about something really unique. Talk about another author. Or maybe your publishers. Or just talk. Make it memorable though. I once had a chat about sex toys. It was the funniest, most memorable chat I've ever had and a whale of a good time. I had a chat once where we spent the entire hour trying to think of a song I had forgot. Silly, huh. But I got e-mails about that chat for months afterward. Some were readers just telling me what a good time they had, some still trying to help me find the song. It was an amazing evening and the most important thing that happened was that everyone there not only remembered my name, but told their friends and the next chat I had twice as many readers.
Now, we all know times have changed and the loops and chats aren't as active as they used to be, but you can still catch a fair amount of readers by just participating on active loops. Don't mention your books unless asked. Simply put your website link in your signature line. People will click, if for no other reason than they're curious about you.
Which brings up another point. Your website is the face of your business. You want to look professional and like you know what your doing, even if, like me, you don't. You'll learn, but your website should look like you've been doing this for years.
The first thing you need to do is invest in a domain name. Using something like wordpress, or blogger, or free webs is fine, but get rid of the blogger.com in the domain name. Most of these sites will help you point your new domain name where it needs to go. Purchasing a domain name is relatively cheap. Most places you can buy a domain name (usually your author name) for about $20. Sometimes less. Just make sure that the e-mail address you use is one you plan on keeping for a very, VERY long time. That is the address they will send you reminders when it's time to renew your name.
Also, consider changing the look of your website from time to time. I don't mean anything drastic, just a new header or color scheme. I'd recommend at least once a year or so. I'll admit, I'm lax in that realm myself, but it's a good idea to keep things fresh and updated.
All in all, your website and your online personality are your most important advertising points. Be memorable on all counts and you'll earn a core fan base that will stick with you and look forward to your next release.