If so, and if they are exposed, nail plywood sheeting to the studs in order to strengthen the walls. On exposed framing, use metal connectors to strengthen joints where beams and posts join. Use nails or lag screws to fasten connectors to exposed framing in such places as porches, patio covers, garages and basements. If possible, remove such items and substitute something lighter, particularly above beds. Guardrails across the front will help keep books and other objects from sliding off shelves.
Rails can be of wire or decorative metal.
Creating a lip on shelf edges with wood trim will also help keep things in place. Remove heavy objects from top. A piece of rubberized anti-slip rug mat trimmed to fit under the object won't keep it from tipping over but will help keep it from walking away. Close hooks by bending them shut with pliers or wrapping them with wire. If you are using heavy plant pots, consider changing to something lighter.