Characteristics of Effective Tutors

How do you know the tutor you hired is effective? First off, chemistry between tutor and student is important. Both must feel comfortable with each other. As the sessions progress, the tutor does less and less, and the student does more and more. I call this the 70/30 rule--in the early stages, I usually am doing 70% of the problem solving on the board, but by our 5th meeting or so, this trend should be reversed--the student should be taking the initiative, holding the pen, working things out while I try and coax the thought process along. My job is done when the student is ready to teach me a thing or two!