i look at other artists around my same skill level who are getting frequent commissions and base my pricing off what they're charging. i find that the minimum wage rule can be a bit misleading because several artists with the same skill will have varying speeds - one might take three hours to do a fullbody, while it might take another ten hours. if the one who requires ten hours to do a fullbody were to go by the minimum wage rule, they'd never get any orders because everyone would be going to the guy that only takes three hours.
if you look at similarly skilled artists and find that what they're charging is way too low for the amount of time you're putting in, consider only offering commissions that you can put out quickly or wait until you're more efficient. for me, selling rendered pieces is a waste of time because similar artists can do them faster than i can and thus charge a lower price. in the time it takes me to finish one rendered portrait for $45, i could do 3-4 animated inked ones and make $100.
toyhouse also has a younger demographic with less money to spend. people prioritize faster, smaller, and cheaper pieces. the sweet spot for commissions here is 20-30$ max. anything more, and your profit drops off very fast. keep this in mind when deciding what commission styles you want to offer - just because you CAN do scenes doesn't mean you have to offer them! it might not make sense for you financially or effort wise.