Good uv mapping tutorial?

I need to texture a building in blender, so that i can import it into Unity, but should I divide the building and create multiple uv maps, or just make one for the whole building. And is there somewhere a good uv mapping tutorial that i can follow? It needs to be for complex meshes, and not just simple cubes. Thanks!

i don’t know about tutorials but i’d try this asset Unity Asset Store - The Best Assets for Game Making which will help you understand how it works