>>20454198I usually look at IRL buildings, distinguish their individual architectonic elements (windows, roof shapes, arches, etc.), abstract those by applying a grid pattern to them in my mind, and once I've got these down in Minecraft, I rearrange them into entire buildings with realistic proportions.
Pic related may be viewed in nature in a survival world here: http://map.dev-urandom.eu/#/55/64/-4742/-1/3/0 