1. No incoming links - Google ranks webpages in part using their formula called PageRank, which is based on the number and quality of incoming links pointing to a page. This principle of rating websites by the number of other sites that link to it is often called Link Popularity, and all of the major search engines rely on this measure when they rank websites in search results. If you have no links from other websites pointing to pages on your website, you will never achieve high rankings in Google, Yahoo! or the other search engines. The most common way of obtaining links is by inviting the webmasters of other websites to exchange links. Naturally, you will have to have created a page on your site to fulfill your part of the link exchange agreement. Other methods include registering your website with one of the many directory websites. Links from blogs, guestbooks, forums, websites' automated links pages, and other low-ranked webpages are of little or no help in this regard. This is the reason I created my Preferred Links system - to create a way to exchange high-quality links. Its simple and free. All you have to do is to comply with 7 simple rules in exchanging links with me that insures you'll be giving a quality link to all of your link partners. You probably already comply with these rules, so sign up today and you'll get a link from me with some real search engine punch.
2. Poor choice of title - Search engine ranking systems give the title tag a great deal of weight in ranking. Don't waste the title by just using your just website name, URL, or some silly phrase that amuses you. Your two or three most important keywords should be in the title of your main page. The title tags on your interior pages should similarly focus on the keywords for ach page. By the same token, don't overstuff the title with every conceivable keyword for the page. Moderation in all things, as the saying goes.
3. Little or no presence of keywords on the site's main page - Search engine ranking software is completely dependent on the text it finds on your webpages. How is a search engine supposed to know the topic of your site if you don't set it out in plain text? A search engine will only find the keywords you feed to it on your webpages. Add emphasis to your keywords by enclosing them in headline and strong tags. I've exaggerated the technique on this page to demonstrate what I mean. A page that is comprised solely of graphics or Flash animation is crippling its search engine potential. Feed those spiders some juicy text! Even a single keyword-rich sentence at the bottom of the page is better than no text at all!
4. tag abuse - A few years ago, search engine ranking systems gave a good deal of weight to the tag, and so every computer book author told his readers this was the secret of search engine optimization. Well, that ship has sailed, and all but one of the major search engine ranking systems now ignore the keywords tag... unless you overstuff it, in which case you could get penalized for SPAMming. Google still ignores all tags for ranking purposes. Yahoo! has retained many of the tendencies of its Inktomi search technology and does give some weight to the keywords and description tag, but again, its not a major factor. Overall, keep your tags short and sweet.
5. Invalid HTML - Writing code that is in compliance with the World Wide Web Consortium's standards means your site is easily read by search engine spiders, easier to maintain, and cross-browser compatible. This is especially important for websites that receive government funding, because the federal government requires compliance with the Americans With Disabilities Act, which in turn means your site has to be compatible with devices that allow the visually impaired to browse the Internet. Using code that is proprietary to Microsoft Internet Explorer is not going to cut it for such sites, so you need to know what is and isn't in the current W3C standards. You can check your webpages' compliance with the W3C's HTML standards using the W3C's newly-improved HTML Validator. Not only will your pages get ranked properly, but you won't have to worry that some users won't see your pages the way you intended just because they don't use the same browser that you do. Don't forget that not everyone surfs the Web with a computer. Cell phones, PDAs, and other devices are Web-enabled now and they don't rely on Microsoft Internet Explorer to display webpages.
7. Poor spelling and grammar - Misspell your keywords and you're negating your search engine optimization efforts. But if you misspell common words, people may lose respect for you and your company. For example, the contraction for the two words "you" and "are" is "you're," not "your." And there is no such word as "alot." You can allot blame for this between parents and schools, but it takes a lot of hubris not to thoroughly proofread your writing. I went to Catholic grade school and the nuns had us diagramming sentences for 5 of those 8 long years. I hated it then, but I'm very grateful now because reasonably good grammar comes to me naturally as I write. The sole exception is to include some common variations of your keywords, if not outright misspellings, in the text of your interior pages in order to snare the search engine traffic from user errors. If you employ this strategy, its a good idea to make it clear that your usage of the alternate spelling is intentional.