One golden rule of packing is to always put the heavy items in smaller boxes. This means books, electronics, that hand painted cement gnome your Aunt Betty gave you, anything that requires storage and has a lot of weight to it. If it is your furniture, that may be difficult, but other items should be kept in small boxes if possible. Always fill the box so that you can safely stack more items on top if needed. Any towels you are not using, bubble wrap, paper, anything to keep the box in its shape and allow for stacking is something to consider.
We recommend using larger boxes for things like a comforter, pillows, blankets and sweaters. They are easier to move when in a box or bin to keep them contained. If you are only using cardboard boxes, you may want to put them in a large plastic bag first to keep them from absorbing moisture and any possible scents they are surrounded by. Another storage hack might be to store these items inside unused suitcases while in transition. If you have a suitcase that you are not using, keeping something lightweight in them is one way to utilize space.