The easiest way to assemble the attic ladder is to glue all pieces at once and then clamp tightly together. Straighten your steps while the structure is clamped so it doesn't come apart. I’m not going to glue the ladder or attic door in place. I’m just going to put the door in a closed position and the ladder against it for mobility without hinging.
I glued the tower roof and kitchen bay roof trims because it won't interrupt the shingling.
I began working on the porch railings and the side ones were the most difficult. Make sure everything is straight and you do not get confused installing so many small parts. If your dollhouse was assembled correctly from the beginning, you should have no issues with alignment.