Figure how much you need to earn each month to get by. Divide that by the number of hours you want to work each month. That's your minimum hourly rate. Now just figure out how much you want to earn in profit.
Personally, I like to charge 2x what I earn at my day job. If I get more than 2 clients at that rate, I double my rate. I'd rather have one client paying me $100/hr than 4 clients paying me $25/hour.
Figure how much you need to earn each month to get by. Divide that by the number of hours you want to work each month. That's your minimum hourly rate. Now just figure out how much you want to earn in profit.
Personally, I like to charge 2x what I earn at my day job. If I get more than 2 clients at that rate, I double my rate. I'd rather have one client paying me $100/hr than 4 clients paying me $25/hour.