what desu said, but I'll go ino more detail
- The render looks to distant, sharpen it up (or unblur it, as you don't see renders that shitty in quality)
- I really like what you have going on on the left, and the overall lighting is appropriate. The background needs more detail though. Look up some background tutorials.
- The render is too "pale". Try duping it several times, distorting some parts of it, and adding different layer effects. You can also try gradient maps like desu said. Image>Adjustments>Gradient Maps
- Obviously the text. I can't really tell you what to do with it because there are endless possibilities, and since your the artist you must choose what to do with it to make the sig look as stunning as possible in your eyes.