For nearly maintenance-free storage units, vinyl is the preferred siding. Vinyl lacks the visual appeal of wood, but if you own a house with vinyl siding, why not select a storage unit that is also sided with vinyl? However, vinyl will get dirty over time, making it even less attractive. Mold is often the culprit. Take into account the maintenance required to clean the vinyl periodically.
Clean It Out - With any organization project, you'll want to remove everything to start fresh. This goes for your shed as well. Toss any old items or trash to declutter your space. If there anything you haven't used or your family has outgrown, now might be the time to donate or sell that item. Though removing everything from your shed might seem counterproductive, it's better to see what you have to store before you create new systems for it.