First, a word of warning about the limitations of SEO: You can optimize all you like but if people aren't searching for and talking about what you're selling, no amount of SEO will help you rank or sell more. Figure out what people are looking for by doing some keyword research. Try tools like SEO Book, Google Keyword Tool or Wordtracker (I also like using Google Insights for trending results. Hint: Search and look at the bottom).
Now, let's talk about what's on your site and how to optimize it. (I consider this part to contribute only about 30 percent to your overall search rank. I'll get to the other 70 percent later in the post.)
1. Write Website copy for humans. Search engines are smart. They know what a real sentence, paragraph, and links should look like. Don't keyword stuff your site or talk about the same things over and over again to try to beat them. It doesn't work.
2. Focus on 5-20 main related keywords or phrases for your entire Website. You don't want to spread yourself so thin you don't rank well for any search terms. Try to "own" the search for a select number of terms. Use the tools above to identify the ones that will drive up the quantity and quality of visitors.
3. Get your best keywords into your domain, folders, and page names. For some great examples of how to create keyword-rich domain names, check out the results for these searches: used cars, monkeys for sale, belize vacation. Folders and pages should also include keywords: for example, http://www.yourdomain.com/used-cars/used-ford-thunderbird.html.
4. Check your keyword density and tweak as necessary. Keywords and phrases for a page should be around 3-5 percent of the total text and links of any particular page (not too much more and not too much less). Don't just focus on your homepage. It's about 50 percent of the search weight of your Website but every page needs keywords to create a "theme" for search engines. The more pages that are ranked, the more entry points your Website has.
5. Make sure the title of each page is different. Mix up your keyword combinations and phrases and don't use more than 70 characters. You can use more, but each word takes weight from another as you keep going. The first words in the title matter most.
6. Include a unique meta description for each page. Include phrasing that has a call to action since it is seen under your title in many search engines. For example: Buy a used car today. We offer great financing for our used cars. To learn more about our used cars, trucks and automobiles call 1-800-used-cars today. Use no more than 155 characters.
7. Style your keywords. Use header, bold, and italic tags throughout your Web pages. These keywords are important and you should show that to visitors & search engines as well. You can style header tags by using some simple CSS to match your Website.
8. Name your Images. Get keywords and phrases into the file names and use them in alt tags, too. For example: used-cars-1965-thunderbird.jpg with an alt tag of "Used Cars -1965 Thunderbird."
9. Link intelligently to yourself. When linking from one page to another on your Website, use your specific keywords or phrases. Don't just use words like Home, Products, Contact if you can use Used Cars Home, Our Used Cars, Contact Used Cars.
10. Create an XML Sitemap. Search engines love them. You can build a quick sitemap for your Website using XML Sitemaps Generator. Upload your sitemap where your front page (index file) is located, then just tell Google, Yahoo, and Bing where it's located at (http://example.com/sitemap_location.xml). A quick way to do this is with a robots.txt file...
11. Create and upload a simple robots.txt file. These tell search engines what you allow or disallow them to add to their search engine. Google has a good description of how to make robots.txt file here. (It takes about five minutes.) Add your sitemap location to the robots.txt and you won't have to submit it to the search engines manually like above. Just add sitemap: http://example.com/sitemap_location.xml to the robots.txt file.
12. Link out. Search engines give more importance to Websites that link to other related sites, especially if they're local to your city or state, or industry. Create a "Resources" page with keyword-rich links out to other sites.
13. Refresh your Website with new content and pages regularly. One easy way to do it: Find related subject RSS feeds and add a couple to your Website too. I like Google AJAX Feed and WebRSS for this, and there are more here.
What you can do on your Website is pretty easy to see; how Google and others tie everything together is not. This is what happens offsite and it's really where the rubber meets the road. Think of it this way: An expert grows their influence and reputation as more people cite their expertise, whether they are a big name in a small niche or a big name in a huge field. The same is true for Websites. And just like people, the more popular your subject matter, the harder it is to get through the noise. Keywords can only do so much; recommendations -- in the form of links -- from influential people and Websites are what will give you a real edge.
Here's how to get links that matter:
14. Ask the right people to link to you. Check the page rank of as many Websites you can find in your industry and start by asking the ones with the highest rank. Link to them first on your Resources page and then email them and ask for a link back. Send them the keyword-rich link text you would like them to use for your Website. Join the Better Business Bureau and your local Chamber of Commerce also -- they usually link to you automatically and this helps in local searches. Check to see who is linking to you by using Yahoo Site Explorer. All of this sounds labor intensive but it's worth a year of your time if it helps you get the No. 1 spot.
15. Create a "Link to Us" page. I have found that if you offer logos and keyword-rich link text to visitors, they will link to you. Here's an example I created for linking to Cloud Hosting at Rackspace. If you do email marketing, email the page to your subscribers and past customers and ask them to link to you.
16. Become an expert on more sites than just your own. Write guest blog articles for your industry on popular Websites. (See how I just did that in tip #15.) Start your own blog and incorporate it into your Website; post and comment on Twitter and Facebook about your industry; answer questions on Yahoo Answers or Google Groups; submit reviews on Yelp, Amazon, ePinions, and Alexa; comment on industry blogs and forums. Link back to your website when it's helpful but don't overdo it.
17. Get listed in directories. They have been around a long time and search engines scan them for new links because of their reputation. Try DMOZ, Yahoo (fee required, but worth it), Business Directory (fee), Ezilon, Best of Web (fee), BizWeb, Gimpsy (fee), Go Guides (fee), Google Directory, or ipl2.
18. Give away free stuff. The more content you can make available for free -- samples, whitepapers, software, tutorials, tips, coupons, contest prizes, etc. -- the more people will link to you so they can pass it on.
19. Syndicate your press releases. Send out a press release locally or nationally when you create a new product or service and link to yourself in it. Here is a nice list of some popular ways to syndicate your press releases.
20. List yourself on Google Places. This means your business will show up as a Google map search result and it carries a lot of weight for local searches.
Getting a higher search engine rank will always be about compelling products and information that is spread by word of mouth. I love what my colleague Klee Kleber, the VP of marketing of Rackspace, says about SEO: "It's a religion." I, like everyone else, have different beliefs on how Google works and we can talk about it until we run out of breath -- but no one knows for sure except the hundreds of Ph.Ds that work at Google. But a strong foundation of great products and quality keywords and links is always the best place to start and build from. To learn more about SEO, check out the best two sources I have ever found at SEO Book and SEOmoz. Keep me updated on how it goes.