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.
If you'd prefer that most of the work be done for you, then just select a shed from your local home improvement store and ask that it be delivered and assembled by the pros. But those who are handy may wish to save some money and order an outdoor storage building kit that comes with assembly instructions.