...if you cannot communicate with your chosen consultant your campaign will ultimately fail. What cannot be communicated cannot easily be managed or measured
Things to look out for
How regular will reports be actioned
If questions need to be asked how available is the consultant on a daily basis
Has the consultant has experience of your industry
Has the consultant references that can be called to confirm all that has been promised
A number of 'gurus' will only do what they are asked and not actually seek out new and better ideas and concepts. Can your consultant do this, are they creative or stuck in the mould of keyword density and a little meta tag tweaking?
Are they on the first page in Google for "SEO consultant"? If not do you really think this consultant can succeed with your website when they cannot even rank their own?