I'm a tutor and have been for a number of years. From my perspective, Wyzant does a great job. I charge what I want per hour; Wyzant takes their percentage for running this service, and I get the rest.
After many tutorings and many good reviews from students of my work, I sometimes get direct requests for my tutoring service.
The best thing is that Wrzant removes me from having to bill the students directly.