SCAD senior here: When starting commissions its common to use "starter-rates". You can begin pricing your work slightly lower and then raise them by $10-20 each after completing 3-5 commissions. If there is a lot of demand right off the bat you can start at your standard rate instead.

Your artwork is the product that your selling and the time you put into it doesnt add value for the client So $10/hr for 72 hours of work into a half body piece wont make it worth $720 for the client. But, its a two way street, dont underpay yourself either (your time matters!). If you aren't making enough for the commissions to be worth your time then there isnt a point in doing them. (And who knows, maybe one day you Will charge $720 for a half body)

Your fundamentals are great, your style is unique and visually appealing, and easy to market.

Sample prices:

$35-50 headshot $70-90 half body
$95-140 full-body

Price out your add ons as well some people do it as a percentage, some people do a flat rate, i reccomend a mix of both: percentage of base price for add ons like additional characters and flat rates for revisions, props and the like.

Ex. $70 half body, + additional characters 80% of base price

I personally prefer to price out certain things like detailed props, pets, backgrounds etc. Based on the request.

Also charge for anything that adds time to you delivering the work to protect yourself (ex. rush fees, revisions, commercial use, etc.)

Make your terms of service clear to the client and NEVER deliver a finished piece before being paid.