Hi,
About lighting, you might want to see/read some tutorials in your free time. When I started to get a real interest in Daz, in Spring last year, I read and watched lots of tutorials, lots of them, believe me. One of the tutorials I saw, after seeing it recommended somewhere, was
this one. It is quite the complete introduction to lighting in Daz Studio. There are lots of tutorials on lighting, both written and filmed. There's not such a thing as too much (video) literature IMHO. The more you learn, the better. I still find tutorials I want to see/read. In fact, I have local copies of lots of them for when I find time for them. And I doubt that I'll ever say to myself that I have nothing else to learn. Of course, you'll need to practice as well. It's ridiculous spending vast amounts of time with the theory if you never put what you've learnt into practice.
About the postwork part, I can't be of much help, I'm afraid. I usually just do very basic light and color corrections with Photoshop's Camera Raw Filter. I think it also depends on the kind of art you want to produce. Some concepts will require most postwork than others most likely. Ron Deviney has lots of popular
You must be registered to see the links
. Many of these can be found here or elsewhere for free.