As I watched the MPC Prometheus VFX breakdown video, I was reminded of one simple fact: Visual effects is often all about layering.
In fact, the more you "mess up" your image, the better it will look. Concerned your 3D model texture isn't going to hold up? Add lens flare, dust, and heat distortion. I've mentioned before how animators added blemishes to Aki Ross's skin in Final Fantasy. You can't have things look perfect; perfect things don't look real.
[Aside: So, why do we photoshop girls? There must be a balance between perfection and purity.]
Keep in mind that you'll go over your effects shots again and again. Your initial wire frame will look very different in your final render. The trick is to learn how to imagine what it will look like and gain the technical skills to get there.
I'm a total SFX noob myself, so it's nice to be reminded that these guys just have more practice and better equipment than I do. With time and tools, I could do something pretty cool as well. If you're interested in visual effects, start practicing now. There are many free tools out there to use as you get started!
Your Media Production Mentor