I used to offer SEO services when I started freelancing. Then I started to learn more about SEO and figured out it was just an elaborate marketing ploy to get inside your wallet.
SEO is actually the practice of spamming search engines, which is likely to get you banned from search engines, instead of a higher ranking.
What I do is called usability. The process of making your website easy to use for it's readers (aka users). If you have a website that people love using, Search Engines will come to you and you won't need to spam them.
In my blog, I post articles which will actually help your search engine rankings as I only use valid, sources who actually work at Search Engine Companies.