For some characters I use
MakeHuman as a base, that gives me a pre-made template for the body and the head, and I can modify those templates in different ways. For some other characters, I like to make them from scratch. For example, today I made this mannequin, I started with some basic shapes like cylinders and spheres, which I then sculpted a bit. It looks kind of similar to those traditional wooden mannequins that you can buy at an art supply store.
Usually, the choice to use MakeHuman or to make a character from scratch has to do with how much free time I have on my hands. If I don't have much free time (due to work or whatever) I'll use MakeHuman to speed up the process. When I have time to spare, I'll make something from scratch, since that way I can keep practicing things like proportions, anatomy, etc.