Many take the optimization process much too lightly. There are particular aspects that do not enjoy so much attention, either from lack of professionalism, or simply because they are not taken into account as seriously as they should. But most of these aspects are the ones that make the difference between a well-optimized Web site and a Web site that will not rank well (or not as well as expected).
Some of the most common search engine optimization mistakes are:
1. Lack of valuable and targeted content
The information that you offer on your Web site must have value for your prospects. Remember that a Web page must contain a series of specific terms and keywords in order to rank well in the SERPs.
Search engines analyze the content and then decide if it is well targeted. If your site is irrelevant, both Web users and search engines will ignore it.
Also, mind your grammar and spelling. Visitors might be driven away from your site, as grammar and spelling mistakes signify, most of the time, carelessness and will influence dramatically the trust that prospects put in you and the information (also services/products) that you offer.
2. No keyword research
At the basis of optimization process stands a good understanding of the market that you are targeting, and of the needs that you are trying to meet. Starting from this, thorough research is necessary to find the exact keywords that will work for your target customers. Don't just slap in your HTML code all the keywords that you can think of.
You may find out (the hard way) that you have optimized your site for the wrong ones. Keyword research and analysis is one "must do" to which great attention should be paid.
3. Improper content for the title tag
Given that the title of any Web page weighs heavily in establishing its relevance to the search engines and that only about 65 characters (including spaces) or less in the title will be taken into account by spiders, bad management of this element can have disastrous results.
The mildest of them is not being ranked for the most important keywords (which have not been read by spiders), while the worst would be getting the site banned for what is referred to as "keyword stuffing" (when trying to squeeze too many keywords inside the tag).
4. Keyword density in the description meta tag
When talking about meta description tags, it is a bad approach to try to gather all the possible keywords in it, but rather try to summarize the web site's content. The description should be a concise and appealing in order to better catch the eye. At the same time, keywords should be present but not in a abundant repetitive way.
5. Not using the heading tags (h1, h2) properly
The major search engines usually look for the titles on Web pages. It is from these places that they get information about the contents of the pages. Therefore, it is very important to pay attention to how these headings are written and what keywords they contain. Actually, they should be written keeping in mind that they should contain the most relevant keywords.
6. Not making use of the alt tag for pictures
Pictures cannot be indexed by spiders, but alt tags can. Keep in mind that they can contain brief descriptions of the pictures that you use, and that they make good places to include relevant keywords.
7. Using images and/or animations instead of text
Search engines spiders only feed on text. Images or Flash animation that is used to enhance the look of a Web page lack the information that search engines need. Whatever is expressed by images cannot be grasped by spiders, and therefore is irrelevant to them. Even if there's a lot of text within an image or Flash animation, it will be disregarded for the above-mentioned reasons. Find out more about this topic by reading an article about Flash and Search Engine Optimization Process.
8. Hiding text
Text can be hidden from viewers employing the same color as the background. But, while people cant' see this text, spiders still can. Such a practice, meant to offer more keywords to the search engines, but without making the page content sound awkward to Web surfers, can lead to penalties.
9. Using framesets
Remember that many search engines do not understand frames. Search engine spiders find is difficult to crawl Web sites that have frames, and indexing is thus compromised. If you absolutely must use frames, then at least add a noframes tag and include keyword-rich text. Search engines can only read what is found between the noframes tags of a frame-based Web site.
11. Failure to use CSS
CSS is a tool that can help you reduce the file size of your Web pages and the amount of time they need to load. You will also get a cleaner code, allowing you to focus more on the text that is fed to the search engine spiders, and also making it easier to modify. CSS is not to be neglected in the optimization process, as it improves the readability of your pages.
12. Page cloaking
This is a technique that is meant to differentiate between the pages that the spiders will crawl, and those that will be seen by people. Common practice is to cloak pages that are extremely rich in keywords, therefore much to the linking of search engine, but that the Web site's owner decides not to show to its visitors, or even keep it hidden from the competition's eyes. The problem is that search engines want to index the same pages that Web users will be able to see, so that they can reference those pages. If cloaking is detected, the Web site risks being banned altogether.
13. Using splash pages
Splash pages, with their big images or Flash animations, contain only a single link, and a redirection to another Web page. Some of the problems with Splash pages are that they lack text, therefore there are no keywords that can be read by search engines, they have only one outbound link and usually no inbound link from another page pointing towards it, and then there is the redirection, which most search engines don't really appreciate and don't index.
14. Exchanging links with banned or promiscuous sites
You should be very cautious about the sites with which you choose to exchange links (it's better to avoid link exchange schemes). Don't just do it in order for your site to be found everywhere the Web. Link exchange with banned/promiscuous sites is frowned upon. Mind you, it influences your credibility and may result in penalties for your site.