My prices differ from commercial commissions to regular non-commercial commissions, but here’s some general advice for the latter:

You have to factor in:

1. The level of your artistic talent.
2. The amount of time you’ll spend on each piece.
3. The audience you’ll be selling the commissions to.

I price my non-commercial stuff pretty low considering the time I’ll be spending on them and the audience I’ll be selling them to.
It usually takes me about 2-4 hours to finish a full body colored commission which I have priced at 60€ (and that’s is cheap if you consider what I would be making at an hourly rate.)

Another good idea is to have set pieces (half body, full body etc.) and set prices. It makes it easier to handle multiple orders at once.
You can also set an hourly rate to work from if you would rather that. :)

If you are unsure of your talent, starting with low priced commissions and building your way up is the way to go.

Hope this helped and good luck!! 👍