There are a lot of variables. One thing that matters a lot, in my experience, is how you light everything. Different kinds and numbers of lights affect render time a lot.
A good place to start learning is one of the forums online where artists post their work and exchange information. Here's a link to another post on this board where a particular forum is discussed:
As someone who is not an artist, I can say that many use Daz3D as a software to create their renders. You can find many models and characters there. There is even a thread about it on F95.
Hello, Friends, You Can Post All TYpe of DAZ3D Art/renders. We Have A lots of Creator In Here. IF u stuck need help. We will Be happy to HELP YOU. Moderation Rules: 1. Do not post any sexualized content involving minors or children. 2. All submitted artwork must be your own. This is to...
f95zone.to
I won't post any direct recommendations until I check out the policy here about linking to other sites.