Load the vehicle you are loading with the items you will use soon first, load the items that are seldom used last; this way, when unloading the vehicle at the storage unit, you'll be placing the seldom-used items in the back of the storage unit and the items you use frequently in the front, for faster retrieval. If you're making several trips between the home and the storage unit, plan to load and store the seldom-used items in the early trips, the frequently used items in the last trips.
Place heavy items on the utility dolly and stack a few together to wheel inside the storage unit; this will save your back fatigue and strain from carrying them. Have a friend or family member help you with heavier objects..
Be mindful in this early stage of packing of where you want to place flat, bulky items such as framed pictures, stiff posters, large mirrors, ironing boards and the like. They'll stack well against a wall. Be sure, though, that the wall is sturdy. Some storage unit interior walls are flimsy; if the neighboring unit is empty, the wall could give way if you stack a lot of weight on it.
Assemble a wall with boxes across the back of the storage unit first. Stack heavy, full, sturdy boxes, such as boxes of books or wooden crates, on the bottom and use lighter and partially filled boxes toward the top. Continue to create walls of boxes in each row. This will give you more space to work with inside the storage unit when placing more items once the truck is emptying.
Review the boxes and furniture you plan to store in the back of the unit and make sure they are all loaded in before moving forward. It is a good idea to make a list of what items are in what boxes on what row, particularly if you don't know how long it will be before you vacate the unit.
Prepare bagged goods, such as clothes or other textiles, and pile them alongside the storage unit as you unload them from the vehicle. Also make a pile of odd shaped and small boxes. Use both to fill spaces where no regular shaped boxes, or large or medium size boxes, can fit.
Place the leftover odd-size boxes inside the storage unit. Lay a few boxes in a shape of a square, stack them about four boxes high, add some of the bags on the top of the odd boxes. Keep laying the odd boxes in fours and keep adding bags on top until you run out of boxes and bags.
Add any heavy appliances or items in a line to form a wall across the storage unit at this time. This will keep the older boxes, odd shaped boxes, and bags together and separates them from the items you may use in the future. Consider stacking a couch or other upholstered furniture on top of heavy furniture. Throw soft or bagged goods, or clothing, in the upholstered furniture's cushioned seats, or remove the cushions to create a sturdier platform for stacking stuff.
Grab the boxes that may be used in the future and place them toward the front of the storage unit in case you want to remove them later. Stack the boxes as high as you can without them falling over. Try to stack the boxes by category, such as kitchen items or bedroom items, close to one another.
Examine the space you have left in your storage unit and consider keeping a path open for you to walk through if you need to retrieve different items. Fill spaces on the periphery with bagged textiles, awkward items and irregular boxes.