Make sure you measure your shelves so that the items you place on them have just the amount of space that they need. This will help you stay organized, make sure everything has its place, and give you the most space possible for storage.
Ditch the cardboard boxes and plastic bags that go with your cereal, snacks and dry goods. They're ugly, take up lots of space and don't keep your food fresh. Instead, opt for glass jars (like HGTV Magazine did here) or airtight food storage containers.