Along side knowing the software and sculpting skills, you'll have to understand how to retopo and other various 3D modeling skill (UV unwrapping, texturing ect.) Unless you're willing to put in years of dedication and time into learning how to use the software, you're best bet is to use Daz3D, it comes at a cost (buying their models) but all the heavy lifting has been done for you, all you have to do is pose, mess with morph targets and render it out. The purpose behind that software is sculpting, which is on a whole different level of experience and knowledge that you would need to acquire.

Though I will warn you that, Zbrush isn't necessary a character creating tool, though that's what it's heavily used for. Other than those, you'll have to create (Blender, Maya, 3ds Max, Zbrush) or buy them (various 3D modeling sites, or Daz3D). There's word going around that vroid is also an alternative (that's if you are looking to create anime characters). Are you looking to create as in making one from the ground up or are you looking for tools to generate characters for you? If you are looking for tools to generate characters for (free) than the one I know of is Make Human.

Daz studio create character