I am new, but from my research I have found that heat, light and oxygen seem to be enemies of hops.
Heat - Best bet is to minimize frost freeze cycles. Deep freezer is best for long term storage. If you don't have that, sandwich them in a cooler with a bag of ice on the bottom and one on top and throw them in your freezer.
Light - again storage in freezer.
Oxygen - ziplock bags are oxygen permeable, so if that is your only choice, double bag. Otherwise use a food saver as said above.