I would suggest editing a sample before quoting a price for an editing project. Factor in the time it takes to edit the sample and the level of editing needed (light, medium or heavy). Also consider how much you would like to earn per project.
Charging per hour can be hard to track (like Canary said above), especially if you are a multi-tasker. It may be easier to charge per word, per page or per project.
Don't forget that you're starting a business by doing this; there are tax implications. You might want to take some time to learn what those are for you, where you are.
Charging per hour can be hard to track (like Canary said above), especially if you are a multi-tasker. It may be easier to charge per word, per page or per project.