1.) Optimizing a site for the wrong keywords

The first step in any search engine optimization campaign is to choose the right keywords for which to optimize your website. If you choose the wrong keywords, all the time and effort in trying to get a site to rank high will be wasted. If the keywords you chose have no-one searching for them, or if the chosen keywords don't bring in relevant targeted traffic to your site, then what benefit will you get from the top rankings

2.) Putting too many keywords in the Meta Keywords tag

Sites which have hundreds of keywords listed in the Meta Keywords tag (hidden at the top of the page), in the hope that by listing all the possibilities in the keywords in the Meta Keywords tag they will get a higher ranking for those keywords, are wasting their time. It won't help. Contrary to popular opinion, the Meta Keywords tag have almost no remaining importance as far as search engine positioning is concerned. Hence, just by listing keywords in the Meta Keywords tag, a website will not really be able to get a higher ranking.

3. Repeating the same keyword too many times

Another common mistake is to repeat target keywords in the body text pages and in Meta Keywords tags. Because so many have tried using this tactic in the past and many still do, the search engines are monitoring this all the time. They can penalise a site which repeats keywords in this way, called keyword stuffing. Simply repeating the keywords over and over again will no longer work.

4. Creating lots of similar doorway pages

Another myth is that since the algorithm of each search engine is different, they need to create different types of pages for different search engines. While this is great in theory, it is counter-productive in practice. Anyone using this method, will soon end up with hundreds of extra pages, which quickly become a nightmare to manage. Furthermore, although the pages are meant for different engines, they will all actually end up being pretty much the same. Search engines are often able to detect if a site has created similar doorway pages, and may penalise or even ban the site from their index as a result. Instead of building different pages for each search engine, create one page which is optimized exclusively for one keyword for all the search engines together.

5. Using Hidden Text

Hidden text is text placed in the same color as the background color of your web page, so it appears invisible to visitors to the site. For example, if the background color of the web page is white and if white text is added to that page, it is invisible and considered to be hidden text. Many webmasters, in order to get high rankings in the search engines, used to try to stuff their pages with these extra hidden keywords. However, there is a definite limit to the number of extra keywords anyone can repeat in a page before it starts to sound odd to human readers.

So, in order to hide it from the human visitors, but still keep it keyword rich, many webmasters added keywords with the same color as the background color.

This ensures that while the search engines can see the keywords, the human visitors cannot. The search engines have long since caught up with this technique, and ignore or penalise the pages which contain such text. They may also penalise the entire site if even one of the pages in that site contains such hidden text.

The problem is that the search engines sometimes end up penalizing sites which did not intend to use hidden text. For example thereis  a page with a white background and a table with a black background. Put some white text in that table. Although visible to human visitors, some search engines can interpret this to be hidden text, ignoring that the background of the table is actually black.

6. Creating Pages Containing Only Graphics

Search engines only understand text - they don't understand graphics. If a site contains a lot of graphics content but little text content, it is less likely to get a high ranking. To improving the rankings, the graphics need to be linked to keyword rich text fso that the indexing robots will know what is in the website.

7. Not using the NOFRAMES tag in case your site uses frames

Many search engines can't process frames. For sites which use these frames, search engines only count what is inside the NOFRAMES tag. Many web designers make the mistake of adding something like this to the NOFRAMES tag: "This site uses frames, but browser doesn't support them". For those search engines which don't process frames, this is all the text that they will see, which means the chances of a good ranking are much lower.

8. Using Page Cloaking

Page cloaking is a tactic used to deliver different web pages under different circumstances. People generally use page cloaking for two purposes: A) in order to hide the propritary source code of their optimized pages from their competitors and B) in order to stop human visitors from seeing a page which looks good to the search engines but does not necessarily look good to humans. The problem is that when a site uses this cloaking tactic, it prevents the search engines from being able to crawl the same page that the users are going to experience. And if search engines get something else, they can no longer be sure to provide relevant results. When a search engine discovers that a site has using cloaking, it will most likely ban the site forever from their index.

9. Using Automatic Submission Tools

In order to save time, many webmasters use an automatic submission software or service to submit sites and pages to search engines. Submitting your site manually to search engines takes a lot of time and automatic submission tools speed that up. But search engines don't like automatic submissions and may sometimes ignore them. But this is changing too

10. Submitting too many pages per day

Submitting too many pages at a time to the search engines can be a problem, and may result in search engines ignoring most of the pages which have been submitted. Submitting one page per day to the search engines is sufficient. While some search engines accept more than one page per day from a particular domain, there are some which only accept one page per day.