Do not hire someone claiming to be any type of GURU.
I read an article recently about people labeling themselves "guru's" of this or that and how they can almost guarantee you success in the social media/ marketing world.
If it sounds to good to be true, yeah buddy it is. The social universe changes daily, new websites, social networks, blogs, new blah blah blah so how can one person have a grasp on the technology? they more than likely follow the website http://www.mashable.com for whats new.
pick a few platforms that you feel comfortable in (ex:twitter, facebook) learn all you can about them to be proficient. you'll save money and the headache