The SEO Pro should be able to do the job with the least amount of man hours or have a team to outsource the grunt work.
I am also a writer for Serpholic Media. You can find some of my articles here: Serpholic Media Blog
The SEO Pro should have references. They should also have a blog or at least have published some articles.
An SEO professional is one who is well-versed in the entire field and can very well implement an effective online marketing campaign.