Ask HN: How do SEO consultants get backlinks?

I hear many different claiming to know SEO and offering SEO services, but I'm curious as to know if they know how to get first page rankings for any website they take on, why not do it themselves and get rich off it? How do they get backlinks? Do they spam it? Obviously not because that would get you banned or would it? What role does web scraping play in SEO? I hear people scraping links or something like that to find out where they are coming from what does this mean? Does anyone have a clear step by step to what they do as a SEO consultant? Say I want to rank number one for "painting service" what would it take to get there? create a bunch of wordpress blogs and link it to each other? Pull a rap genius? What things can be automated?