[TomGreen]

I would add that, as with many things, the more you know about SEO, the better able you will be to hire the right person for the job.

Some people will be very open about techniques in any case, and those are the people you're better off dealing with. But in any case, your contractors need to be accountable to you; so if you understand what you need, you can talk to your contractors about it, get feedback and recommendations from their expertise, and get the best out of your investment.