I am not much of a position to give advice but I agree with PyrZern, the golem on the concept looks like it was made of rock, the body of your golem looks very organic, and the rock on his arms is a bit out of place "material" wise from the rest of him. *for high details, have you look into HD geometry?…
Yeah, I probably went a bit too far with the wear effect . Just had some fun with it =) Anyway here how I did it: 1. Create a plane with the same proportions as your image. You can do it in maya as well. I did it inside zbrush by just scaling a plane with gizmo. 2. Open the plane in zbrush and subdivide it to about 6 or 7…
The normal map material tristamus is talking about is here under the effects tab, 3rd row - http://pixologic.com/zbrush/downloadcenter/library/ Did you also turn on shadows when doing a BPR?
Also see the Zbrush classroom videos. Free, and high quality, right from the source. They don't cover game-specific workflows, but they're the best at showcasing Zbrush itself. http://pixologic.com/zclassroom/homeroom/
Zclassroom is probably the best you're going to find anywhere. They cover specific modeling subjects too, not just the button-ology. http://pixologic.com/zclassroom/homeroom/#digital-sculpting
LOL @ Paradan. As for sculpting: Have you looked into Scultpris? http://pixologic.com/sculptris/ I've found it rather handy. Its not as uberpowerful as zbrush, but it certainly gets the job done. That said: aside from woodgrain, you can do plenty of the higher poly stuff you want in your regular DCC app.