Freelancers/self-employed IT-consultants, how much do you charge per hour? Also, do you have any certificates or other things that boost your pay?

There are so many factors to arrive at a rate. Where you're based, qualifications, experience, existing clients who can vouch for you.....

It also depends on the work and the client. Are you going to be paid upfront? Payment fees?

Or clients generally have an idea of what they're willing to pay and don't care about cost as long as it's less than that number. When I started out, and it was just me, I felt I was competing with freelancer.com types and that the best way to earn a living was to keep the rate low.