Well, Terminatural, my only tip I can suggest you is to start modeling very basic things to learn Blender and then, as ai said, we could help you to import your future model in Nexuiz. I suggest you to read this
guide and, when you learned all basic tools and techniques in Blender, you'll be able to start learning advanced techniques, like described in this
DVD. I think that in Nexuiz is very difficult to achieve that result because Unreal Engine 3 has an advanced lighting and shading system that is not replicable in Nexuiz. However, starting something is always difficult, but future results are possible only with effort and training!
Good Luck
PS: I disagree with Sepelio, Blender is not more difficult despite other 3d apps, it's just more tied to shortcuts instead of menu commands, but, once you start to understand the "hood" beneath the software you'll understand that is one of the open source pearl in this universe!