The website that contains contents that is specially designed for the search engine and some thing very different for your real user is called cloaking site. The search engine works by validating IP address and linked keywords of the search query. In the cloaking techniques, the homepage is distorted to each and every keyword to make search engine think that your site contains very relevant contents especially designed for the queried keyword or key phrase. Cloaking can result in a penalty that may damage your business as well as ranking. So it advisable that avoids cloaking, if you really want to be in the good list of the search engines. Before few years back cloaking was a much glorified issue, but in latest technology added in the search engines, it itself recognize the cloaking and other unethical forms of SEO. Try to avoid cloaking as much as possible.
You should not go with those SEO firms who give assurance of achieving you a first rank in Google or other search pages. Because no firms can promise you assurance such rankings. Even top search pages has quoted that they don't tie up with any SEO company, hence there isn't any point relying on such fraudulences.
You have not to submit your website to search engines every month. Post your website once and wait for few weeks to get indexed in the search engines. Sometimes it might take months to get listed in search engine's pages. Don't submit your website every week or month as this might hurt your website's image. Few firms use software that automatically submits your website in regular basis in weekly or monthly bases in search engines. This will bring the list of penalty, once you get caught by any search engine.
SEO is task which required lots of patience. It needs your patience also. It is time consuming and an ongoing process. If you are thinking that you can reach top ranking in any search engine in two days or two weeks time, then it totally myth because it needs time to get stable in the search engines. You should have enough insistence to attain a good rank in search pages. Don't be have attracted by SEO firms who guarantee thousand search engine submissions. Because many firms targeted your money to earn. Don't waste your time on finding such guarantees. Be firm in your approach and have the courage to press on.