To be sure I choose a reliable SEO, what questions could I ask to feel more confident it is the right one? If I ask "how or what" then obviously they keep it vague (which i understand, nobody wants to actually TELL the techniques). Anyone? Thanks!!
Will my website need to change? How can I ensure you’ll operate ethically? What is your process for keyword research? What things do you look for in a search engine friendly site? What steps do you take in optimizing a website? What is your overall approach to back linking? What is your pricing and when can I expect (ranking) results? How will I be able to gauge progress, and what level of communication should I expect? General SEO Experience? How long will our agreement (contract) last? What should my SEO agreement include? How long do clients typically stay with you? What do you need from me during the engagement?
Asking for references and sample work will be a good idea. Agreeing on campaign deliverable before actually signing a contract is a must.
Personally I would be a bit concerned if an SEO wanted to be too vague about the "how or what". I've never been in the situation of spending any real cash on an SEO consultant, but I would never just hand over a domain for SEO work without knowing a fair bit of the game plan. I'm unsure if this vagueness is a bit of an industry standard, but my guess is any SEO worth salt should be able to give pretty good insight into what they are going to do without revealing too much about what it is they believe gives them their competitive edge.