Follows are the three Don’t when perform Search Engine Optimization:
SEO may helps you to submit website, may helps you to edit your web copy. But the most important part of SEO is keywords selection. You know your business and targeted customer than the SEO company do. So, do it yourself. Talk with your customers and ask their opinion on keywords, and glossary to describe your products and your company.
You only need to target those famous/big search engines. The effort spends on submitting to the rest of hundreds may not brings you a customer. It is because their traffic is so little and not hit your target customers. Moreover, those search engines may rely on the result of the big one. If your site is listed on the big search engines, it maybe listed on the small one also.
Repeat submission to search engine provides no help to your website ranking. In some cases, repeat submission may even be marked as spam and result in lower ranking. Put your efforts on other areas, like keywords selection, proofread your web copy, etc.