How do you keep unfaced insulation from falling down?
The friction of the fiberglass insulation material against the rafters, baffles and plywood or wood slats is typically enough to hold it in place. You can assist the friction hold by adding metal wires or bands on the inside of rafters near the edges.
How can I secure my attic insulation?
Here's one good method. Staple long pieces of duct tape (sticky side up) onto the attic scuttle door. Then add insulation batting to form a pillow and wrap it up like a birthday present as shown. Add foam insulation tape around the edges to seal the perimeter where it rests in the access hole.