My ceiling is kinda high in places, so it can be awkward to get up on top of a step ladder with some of the models...

For some of my smaller models I have just screwed hooks into the rafters and then used bungee cords (with protective foam) to hold the models in place.

For slighter bigger models that are awkward to get up high, I have used miniature pulleys and 1/4" rope to set up a system whereby I just put the model on the floor, put its harness around it, then haul on a rope that will hoist the model up to the ceiling.

Gordon