People have already mentioned your lighting. But overall, your skillset could be improved. 3D Sculpting, High poly sub division modeling, texturing, baking clean normal maps, etc. These are all the higher tier skill sets that will really make your work pop. I'm still fairly inexperienced compared to some of the other guys…
Personally, I'd look into millenia's tutorials over racer445's. Racer's are a little fast and it's more of a "hey look what I can do" Also, for a crit: your titanic model, the windows are a little wonky. Some are stretched more than others. And the portholes on the forecastle arent that big. And you're missing the anchor…
Firstly those new shots of the Blitzball stadium I promised before my internet died :S http://imgur.com/a/8kYk3 To dtschultz : Don't worry, I do see the difference in the images, its how to achieve them that I don't really understand. For example I wouldn't know how to start getting the textures to start looking correct,…