SEO is one of the economic ways to get your url listed on the top of free search engines. That is why SEO become so important. There are tons of guidance in SEO on the internet. But in the other hand, there are also misguidance in SEO. They always say to optimize, optimize and optimize your web page with keywords, without considering another factors like determining keywords or phrases keywords effectiveness, how many times you should repeating keywords on your page, etc. What I want to tell you is, that's not enough. If you want to get effective search engine optimization, then avoid these mistakes:
1) Using wrong keywords. What I mean with wrong keywords are using certain keywords or phases that have no effectiveness in value. Using these kind of keywords will bring you thousands of competitors (not visitors) and make your site stink.
2) Keyword density exceed than 5%. It is true that to get the top on search engines, you need to repeat keywords several times on your page. But, too much repeating keywords on your page will make your site being penalties, since search engines assume it as spam. Just follow the thumb rule: keyword density may not exceed than 5%. This is the safe way to get your url listed on search engines. If you have any difficulties about this, simply, divide the keyword with the numbers of total words. Multiply the result with 100%. Now you got it.
3) Hidden texts. Hidden text is text that has the same in color with web page's background and this is a part of spam. Many web masters use hidden texts technique to increase keyword density. Indeed, these texts is unreadable by human visitors but, spiders can recognize it.
4) Too much images/flashes. This is another mistakes of building web sites. Many web masters use images and animations in their web site to attract visitors. It does make their web sites dynamic but, search engines can not see even an image on their site. They don't realize that search engines are blind. If inserting an image become so important, use it's alt attribute so search engines robots can read the alternative texts. The alt attribute itself have to represent keywords you use.