When designing characters for my comics, I create numerous test renders. I don't save all of them, but here are some from Mannequinizer that I did save.
Sometimes I'll have a figure in my library that fits what I'm looking for, and I just load it and use it. More often than not though, I'll find a figure that comes close and then play with the figure morphs till I get what I was envisioning. The last image in this post was what I stared out with for Dawn's sister, Sara.