What are the most important things for a legitimate professional search engine optimizer is to check all of the HTML tags for a page and make sure that they are optimized. If you cannot understand what HTML is then we have the whole information for you in simpler and easy words, it is the code that makes up a web page. It is actually a tool to change appearance of the site. If you want to change the appearance of the site then there is a variety of tags available.
Search engines display different kinds of listings on a search engine results page (SERP), including paid advertising in the form of pay per click advertisements and paid inclusion listings, as well as unpaid organic search results and keywords specific listings, such as news stories, definitions, map locations, and images. This Online Search Engine Optimization is concerned with improving the number and position of a site's listings in the organic search results. Broadly speaking, SEO may be geared towards increasing either, or both, the total number and quality of visitors from Search Engines.

Online Search Engine Optimization by 101SearchEngine.com