Here, I write following points that describe reducing search engine technique.
Link Farms – link farms mean it to be a catch all for bad links which are pointing towards your website.
Duplicate (Copy) Content – Google doesn’t allow link duplicate content on site. IF your content match with other contents of other site then Google not allow you to gain your site rank and it is consider as copy content of other site
Canonical Issues – The good thing to do is to make sure that you choose one URL and stick with it whenever linking back to your site. If you forget this and accidentally link to two or more different URL for your main page, it may direct to the same place.
Flash Web Sites â€“ If you use flash than difficult to crawl your site. If you use a flash introduction this can have disastrous effects on your SEO efforts and ranking. Flash introduction is look cool and good but it also gives cool traffic for your site.
Other point that I describe bellow is also affect the ranking of SEO
Lack of Content, Broken, etc..