Stand 'em up with their spines perpendicular to the ground and keep 'em in a temperature and humidity controlled environment and you'll be fine. Don't pack 'em too tight together and do not lay them flat.
Al suggestions solid so far. Would go a step further by not only keping them standing on the bottom edge and keeping them out of high humidity but out of excessive temps and avoid all sunlight. If they have paper sleeves you might want to replace them with plastic sleeves and if the covers are imortant to you as well place them in plastic covers as well. In bulk they are easily affordable and worth the investment.