Unless you're transporting beach balls rather than breakable items such as your grandmother's china, you should prevent the trailer's contents from moving during the trip. Shifting cargo will not only be damaged by the wild ride, but also cause the trailer to sway as it's towed, and that's a major danger in towing.
One way to prevent shifting is to pack the cargo tightly together, leaving no room for it to move. If you're not a master packer or you have unwieldy items, tie-downs may offer a better solution for securing cargo. Tie-downs can be straps, bungee cords or rope. Bungee cords will stretch and apply pressure to the cargo. Cargo nets use many bungeelike strands to keep the cargo safe. Ratchet tie-downs use a locking ratchet mechanism to tighten the strap and secure the load. They attach to openings, attachment points or eyeholes on the trailer. They can be found in many hardware and auto parts stores, and they're inexpensive compared to the cost of replacing damaged items.
Now that everything's loaded and secured, you might want to consider investing in our next towing accessory.