I've found SEO is just writing authentic, good articles that people link to and want to share cos they find it interesting. My best results come from genuinley good articles

But there is of course the automated SEO bits, like generated 'alternative to' pages, good meta tags, article titles. I think most SEO tactics can be found in a blog post. Unless the consultant is writing good articles or doing the work for you, I would hire contractors and give them instructions