Let's try something simple for a start.
Here are some pictures from my noble elf pack that probably should give you the idea how these random characters should look like (of course you can also download the whole pack if you want to). Hairs and faces don't have to be
exactly the same as at the pictures, it's a random, generic character after all.
Would be cool to have in the future multiple packs with different boobs and hair colors, but for now as a test let's make a character like on those pictures. Ie a tall one, with long blonde hair, quite big boobs, green eyes. And with a white background for now.
Also there are some basic poses and clothes. Try to render profile pictures with those clothes, ie when the character just standing doing nothing. And try to render sex scenes based on pictures, without clothes and preferably with unrecognizable partners, when you can see body but not face or hairs.