Here's what I have been doing, and it seems to be helping:
1. MOST IMPORTANT do keyword research. Both through a KW research tool (I use Market Samurai and love it) AND look at your stats what keywords your visitors are finding your site through.
Make a list with your top 5 keywords, and a second list with secondary keywords. Mine is about 20 keywords long.
2. Go over your content. Bold or italicize some of your keywords. Link some of your keywords to other relevant content on your site. Say you were writing about apples, and your article says something like "apples are not oranges", make sure you link the word oranges (or the whole sentence) to your article about oranges. Look how your taxonomy is set up and maybe make nice taxonomy landing pages. Make sure that your content urls have keywords in them, and not example.com/?=321 or your article about apples is not example.com/shiny-red-fruity-things. It should be called example.com/apples. Your taxonomy should be example.com/apples/granny-smith. DO NOT DELETE YOUR EXISTING CONTENT URLS.
Use a module like URL aliases to rewrite your content paths VERY carefully.
Check if your primary link navigation structure uses your keywords, and if not, think about how you can change the titles of your menus to reflect this, using url alias to do so. DO NOT DELETE THE OLD PATHS!
3. Go over your meta tags. Use your keyword list and change the meta tags for EVERY page of content, making sure they are relevant to the content. Make sure every piece of content has a description tag. Depending on your blogging software
, there is surely a module that can help you with this.
4. Different page title names for each piece of content. Not the article title, but the page title (upper left hand corner of your browser). Get those keywords in there and make each one unique.
6. Make sure your sites are listed with Google, Yahoo and Bing. If they aren't, submit them. If they are, regenerate and resubmit your site map after doing the above 4 steps.
7. Bookmark your content. If you use Firefox, there is an add-on called shareaholic that makes bookmarking content easy. Just right-click on your article and you get a list of places like reddit, delicious, digg etc that you can post your article to. Do this for each piece of content.
8. Taking your list of keywords, get yourself a hubpages and squidoo account and make a few relevant pages on each site. Make sure on hubpages that you have at least 6 modules on your page and that you only link back to your site once (either the RSS feed or the link box). Same with squidoo. If your hubs/lenses are good, you will see yourself getting some traffic from there, and google likes these backlinks.
9. Other off-page SEO practices, like commenting on other relevant blogs (only well-thought out comments, no spam!), getting .edu or .gov backlinks (google inurl:.edu + keyword) and see if you can find anywhere relevant to link back to your site. Use your signature in relevant forums but DO NOT spam the forums. I actually get a LOT of traffic from forums that I use privately i.e. don't talk anything about my sites but people are nosey and will click on your sig links.
10. Read "Article Marketing
the right way" by Lanadili http://forum.abestweb.com/showthrea...ghlight=article
and do it.
Don't forget to add your site to your email signature!
And then, if you so desire, learn about Pay Per Click and how to do it properly. I burned a bit of money on it earlier this year, so I try to stick to onpage and offpage SEO right now.
There is also a great web marketing checklist that I wrote about last week. You might want to download it, print it (or use Adobe for an interactive checklist, thanks Daniel!) and go over your website with it.
Hope this helps!