Submitting your site to a search engine or indeed getting it to enter your site within its results is a simple procedure however, in order to maximize the usefulness of your site ie get traffic and actually make it work that much harder for you, means it will need to rank well and at the very least be found as easily as/along side your competitors site.
This can be achieved through good optimisation but be aware that the more competitive your search phrase the more optimisation and importantly, time will be required to bring about these desired results.
Search engines each have their own ways to obtain their search results eg algorithms & guidelines and to display relevant results for the searcher they use several key features within a web page to return these results. Thus, to rank well these key features need to be included and managed within your pages on an ongoing basis. Bear in mind that these features are not automatically built-in when a site is designed and that just because you have a website it does not mean you are going to get traffic.
Take note that search engines frequently make alterations to their algorithms/results which in turn alter the ranking of web sites. An optimiser can add features to an existing site and will be up-to-date on such requirements.
Could you undertake the optimisation of your site yourself? This would require access to your website's code, copius research and time to implement. We all have only a single pair of hands and your own time may be better devoted to existing or other planned business activities.
Would you want to undertake optimisation yourself? There are also things that could be done by the inexperienced that would lead to a ranking penalty or even ban from the search engines.
Optimisation is not as straight forward as it may first appear as each search engine needs to be catered for as well as a balanced look & feel to the site maintained for the benefit of your human visitors.
In addition to the benefits already outlined, using a search engine optimiser to optimise your site is far more cost effective than hiring an additional employee and more reliable than detailing either yourself or an exisiting employee to undertake the task.
Reports can be undertaken to establish your positioning both prior to, during and after implemented optimisation. A good optimiser will be clear about what is being done with your site and will work with you to improve your ranking results.