I admire your stubbornness then - if you really want to jump in the deep end and try it, by all means have a go.

Setting a very difficult goal for yourself is a great way to achieve the best you can I find.

As to how to go about it, I would recommend that you begin by modifying the original.
This probably won't become your final one because working with an existing model is
very tricky - especially for a beginner. I'll say right off also: totally ignore textures for now. Don't worry about them at all and concentrate 100% on getting a feel for modeling, because Blender handles textures kinda weirdly and it will more than likely just hinder your modeling at this stage.
So yeah, just try adding all sorts of bits and pieces to the model. Start with something like antennae, move on to things like squarish extrusions, cutting recessed areas, pipes here and there and just keep on adding complexity to what you do until you're able to 'spruce up' just about any existing surface.
That's a good way to get into the feel of greebling, and will give you a lot of what you'd need to build basic hull structure. Later on, you'll probably find the existing model too time consuming and limiting in what you can modify, and at that point I'd recommend starting from scratch.
From there you'd use the original model as a shape guide while you construct a more complex basic hull mesh. This is what I did with the lucifer and it turned out ok-ish, but I learned a huge amount from it.
And actually - that's the key to modeling really - treat every model as a learning experience and you'll find you can soon model any shape you can think of, and even a lot that you can't

If you have questions, need help, tutorials, advice or anything I'd be happy to give it.
