Typically, I like to work in stages.

Firstly, I'll google reference images so I can get some inspiration. For example with my Stargate build, I went and watched a few episodes of SG-1 (Loving it so far). Secondly, I'll make a plan of what I'm going to build, this is usually on a physical notepad next to me, as I like to interpret and design what I'm making with my own hand, rather than a mouse.

After that, I'll go about making the foundation of what I've built, and then add lighting. After that, I'll add the necessary details and then seek peer feedback on the finished product, amending or altering it as they advise. At the end of the build, I often end up with many copies of one product with slight variations, and use the one I'm happy with.