Old spices never go bad, they just fade away: Spices must be stored properly to maintain strong, fresh flavor. Heat, light, moisture and air all speed the loss of flavor and color.  Here's some tips I've picked up that might help you. 

 The Do’s and Don’ts of Spice Storage and Usage:

• Do keep your spices out of direct sunlight, hot air and humidity. These factors can alter the flavour of your spices and shorten their effectiveness.
• Don’t store your collection above or right near your stove range- it’s the #1 worst spot for spices precisely because it’s hot and humid (think boiling pots of water, soup etc…).
• Don’t store your spices near any other heat source: dishwasher, refrigerator, microwave, heating vent, direct light or the sink.
• Do keep your spices in an air tight container- you lose depth when spices are exposed to air. Make sure the seals and lids are completely closed when finished using them.
• Do keep your pre-ground spices for approximately 6 months to 1 year. They don’t go bad per se, they just lose their flavour profile and adding more won’t give you back the flavour you’ve lost to time (sounds like new age advice, but I can vouch for its accuracy in my less experienced culinary days).
• Do keep whole spices for up to 3 years. If you purchase a mortar and pestle, you can easily and quickly grind your own and fresh is always best. You’ll know when you bought the spices and when you ground them each and every time.
• Don’t buy in bulk unless you’re a commercial outfit with a high spice turnover. You won’t use what you buy before you’re left with tasteless powder.
• Do keep your herbs for 1-1.5 years- with good quality dried herbs a little goes a long way.
• Don’t shake your shaker top spices into a pot or a sauce pan. It’s one of the worst things you can do to your spices (see above for hot air and humidity). This applies to shaking them over a hot food item.  
• Do set aside a small dish and shake/grind/pour what you need into it before heading over to a hot pot with it.
• Buying at bulk stores may not always be smart. Sometimes the bins are refilled, mixing old with new. Purchase bulk herbs and spices at a reputable store that enjoys high traffic. With greater turnover, the spices are likely to be fresher. Cellophane and plastic packaging is not completely airtight and lets light in. The herbs could be beyond their prime before you even open them.
• For spices that tend to clump (such as onion and garlic powder), add a few grains of white rice. The rice won’t affect the flavour and is too big to pass through the holes, but will help absorb any moisture.

(ps. I don't take full credit for this article. I just can't find the original source for many of the points. If you find it, please let me know! Thanks!)