I was asked the same question about a year ago when I got hired as a photographer assistant to the photo shoots, plus I do all his graphic work/touch ups, as well as his marketing. We settled on $25 per hour. Without the marketing (which takes up an insane amount of time) I would have started at around $15 to $18 per hour. I hope this helps.
Kill a man, you're an assassin.
Kill an army, you're a conqueror.
Kill em all, you're a god