Figure out a per project price. Define it in a way that protects against scope creep.
Try to separate price from hours worked. If you get better and faster, the same price per project gradually becomes a better hourly wage for you.
Clients don't necessarily know nor care how long it takes you. They care did the task get done.
You need to have some idea how long things take and some tolerance for things taking different amounts of time. Keep your pricing structure focused on tasks or projects.
Charging by the hour when you aren't their employee is always all kinds of headache and neither side is happy. The client ends up feeling overcharged because they can't track your hours and you end up feeling underpaid.
Charge per task. Get good at defining tasks in a way that makes you happy with the pay.
Expect to not always get it right. Be kind to yourself when you don't. View it as a learning opportunity. Do some analysis of what went wrong and what you need to do different.