If you're renting self-storage there are a lot of things you can do to maximize the amount of space that you use, this means you're renting the size space that you need and no more. The specific things that you need to do may vary depending on the type of items that you're storing, but for most miscellaneous items as well as medium-sized pieces such as lamps, boxes will suffice.
First, you need to identify the kind of items that you want to store. If you're wanting to store furniture, it's a lot easier to disassemble it to allow for extra space. . Unfortunately not everything can be disassembled, but even in those cases there are ways in which you can use space efficiently.
Ideally putting all smaller items into boxes works best as they tend to store and stack a lot more conveniently than anything else.
You will normally put items into boxes according to category. More specifically, items that are more fragile should be grouped together with other fragile items. The same applies for heavier, more solid items.
Besides item category, you'll also need to make sure that the smaller items remain on top, so that weight from heavier items won't end up collapsing boxes underneath and causing damage to your property. Importantly take note of the items you wish to access frequently and keep these in a box or container close to the front of your shed.
If your furniture is going to be held in storage for a period of time it is worth investing in covers or plastic to protect them from dust.
A big part of putting items into storage is making use of labels. If you don't write down what each box contains, and weeks or months pass by, you're going to have a hard time determining where you put everything.