Proper packing is your best insurance against damage. Here are a few packing tips.

Pack as much as you can into boxes. This will provide greater protection for your belongings and will make loading your trailer much easier. 
Don't skimp on packing supplies. They are far cheaper than broken or damaged belongings. 
Reinforce the bottom of all boxes with tape. Fill each box to its capacity, using paper or fillers to eliminate empty spaces. The top and sides of each box shouldn't bulge, nor should they cave in when closed.
Start packing several weeks before your move date, taking it one room at a time. Begin with things you use less frequently, such as books and knick knacks. Pack each room in separate boxes and label each box with its contents.
By following those advises you will assure the safe move of your items.