Gray Hat SEO is about risk versus reward. Some Gray Hat SEO services tend to use more dubious devices and take bigger risks. Gray hat SEO is SEO techniques that take more risks than white hat SEO techniques but aren't likely to get your site banned from search engines (although a search engine penalty could result).
There are lots of factors which are necessary to improve the search engine poisoning of the website. Some of the major things are explained here. Its very important to focus on key phrase rather than a single word. Keyword density is also a major factor which Bing sees. Submit your website to different open directory projects. Social networking is also important for promoting a site. Always keep the flash minimum in your site.
After Google Panda and Penguin updates many of peoples think that SEO is now dead but its just their imagination, according to me, and my experiance till yet now SEO is based upon only on quality and authority work, don't use the grabing or scam or spun articles just unique content is the king, and the links from low PR websites are now cancer for the authority or your money site. Just tries to get the links from High PR websites and sue lot of social signals.