Move It Out - When organizing your shed, it's important to consider what you use it for and the climate you live in. Keep in mind, many sheds are there to protect your items from the elements, rarely are they insulated enough to protect against extreme cold or heat. If there is anything currently in your shed, such as paint or liquids, you'll want to move those to a place that is more temperature controlled. Additionally, any pet food or paper is surly asking for a visit from any pests in the area. Move them inside the house where you can ensure their quality.
Organize For the Season - Now that you know what's staying in your shed, you must consider when you use the items. You don't want to move a stack of gardening tools just to get to the snow shovels you'll need in the winter. If possible, dedicate one side of the shed to warm-weather specific equipment and the other to cold-weather equipment. This will alleviate any confusion on where items are and save yourself plenty of time when working.