Cinnamon, nutmeg, cloves and other spices often used in baking. This video guide from America's Test Kitchen will walk you through when they're best applied, how you should buy them, and how you should store them.
The video covers cinnamon (specifically the difference between real cinnamon and cassia, the spice most of us are getting when we buy "cinnamon" at the supermarket), cloves, nutmeg and ginger, along with the best applications and storage methods for each. Even though the piece is focused on baking, the ATK folks also explain other uses for each spice, like studding roasts and hams with cloves for extra punch, as opposed to using ground cloves for baking.
Also, always buy the smallest containers you can get of spices. That way, you actually go through them as opposed to risking them losing their flavour by sitting in your cupboard for years.
Things You Should Know About Baking Spices [America's Test Kitchen]