SEO related to building a search engine friendly site first, before the programming. As someone previously pointed out, when you are learning something you could learn bad habits, which you have to undo when you know better.
The reason is, generally, a programmer isn't involved with the actual content creation, just the functionality of the site from a programming point of view. With your search engine friendly program construction you will give your clients a starting point to build from.
From that point you can expand your services to include other aspects of search engine optimization.