Tape the bottom of every box; tape the top closed tightly when full. Run two strips of tape along the side and one strip down the center. (If the box is still not strong enough, apply more tape on the sides.)
Use small boxes for heavier items; larger boxes for light weight, bulky items.
Wrap small and/or fragile items individually.
Stuff top, bottom and sides of boxes with paper. This helps prevent shifting, rubbing and possible breakage.
Stack boxes to the top to prevent them from being crushed. But don't pack fragile items too tightly. Stuff with paper.
Label the contents of every box and the room where it belongs. Group boxes together that belong in the same room. Label any boxes/items "STORAGE" that will be stored for you.