When you receive a proposal from most web agencies, you'll see an extra line for Search Engine Optimization. You may think that this is a great thing... the company you've chosen knows exactly what you need, right?
Search engine optimization is not so much another line item as it is a process that should be incorporated into every step of creating your website. SEO should be an integral part of any agency's development process from conception to completion.
When outlining your site architecture and page titles, SEO should play an essential role. Be sure you're using the most descriptive and search-oriented key phrases you can. Your URL structure should be clean and readable.
Each and every element of your website should be designed with SEO in mind -- where are the h1 (Header 1) tags? h2 and h3? Where is your navigation and what are the titles of each page in that navigation?
A large part of SEO is the way in which you use HTML. The appropriate tags should be used in the proper places. For example, because a search engine can't see images like you can, you must assign descriptive alt tags to every image.
This is an easy one. Your content needs to be created and published in a search engine-friendly way. Your topics should be interesting, your content should be of quality, and your writing should be precise.
Like with any aspect of your digital presence, SEO requires ongoing attention. Because the Internet (and technology as a whole) are constantly changing, your site needs to be constantly maintained and monitored in terms of SEO as well as general code, design, and function.