After the thumbnail process was complete, I drew my first choice for the house design. You'll note that I used pen and paper - These interim steps are for me, not for clients, and tool choice is almost irrelevant. Do it however you feel like, the important part is to increase your understanding of what the thumbnail represented.
To make sure my understanding was there, I chose to make notes. This can be a really good idea if you want to share with an AD or teammate before you go further.
After the drawing was done, I jumped into 3D-Coat. Because of the voxel nature of 3D Coat, it is great for loose 3D sketching, but pretty heavy on system resources. For this reason, I went back and forth on if I should model the entire structure as one thing, or build it in components. In order to keep sizes consistent, I opted to create each part as a separate section, but then down-rezzed it and made a *very* low-poly reference model of the entire thing. This ended up being a very good thing for me, as during the the texturing phase I accidentally overwrote one component, and having the entire house let me recreate it very easily.
There's the fundamental design for the house! The next stage is to quickly texture the sections in 3D-Coat, and then bring them into Unreal Engine to render with an environment.
If this were a studio project, I would definitely share what I have at this stage, as it would be very common for the AD to have notes of things to change, and this sketch phase can be very iterative. Since I'm my own AD, I have the advantage of saying, "Yes! You knocked it out of the park!" on the first pass :)
Next step, getting ready for the final painting!