You charge what you think you are worth. If you charge too much you're taking advantage of someone BUT all is fair in business. If you charge to little you're taking advantage of yourself BUT all is fair in business.
I would make it a point to not charge for learning. Charge for the project yes, but if you spend 3 hours on the project and 3 hours more learning how to complete the project I would make sure to not charge (at least full price) for learning.
That's my 2cents
When I started I was charging $20 an hour but that was 6-7 years ago. You could also do per project pricing. (calculate expected time + hourly wage = per project price)
Partner / Production Manager
iMotion Video Corp.