By Veoline
 

I hope what I am saying will help !

By Veoline
 

Or you can use building parts as windows and doors, by sinking them into the structure, then coloring them, and eventually add more details, to save some complexity.

By Veoline
 

Nice ! There's much more detail now ! But i still have one more advice : You don't need to use the details as such. You can use windows as doors, for example.