Even wedding dresses that have been sitting around for decades can benefit from an expert cleaning. But the best way to preserve your dress is to clean it as soon as possible after your wedding – ideally before you jet off on your honeymoon. This will help prevent stains from setting in and becoming permanent. Even stains that you can’t see, like perspiration, can immediately start to damage the delicate fabric of a wedding dress.
Gowns should be cleaned by a wedding dress specialist who understands the unique needs of wedding dress cleaning. (The local dry-cleaner isn't usually the best choice).
After proper cleaning, wedding dresses should be stored flat or folded (not on a hanger because the material will stretch over time). Don't store the dress in direct contact with any wood fiber - like cedar or cardboard - as this will result in a stain. (Acid free paper between your dress and the box will prevent this). And make sure that air can circulate around the dress so that the fabric fibers have room to breathe (plastic bags and vacuum sealing are out).
The actual storage location should be a temperature controlled (no extremes) room and away from direct sunlight.
Remove the dress from storage and air it out a couple of times a year to check its condition. (Resist the temptation to put it on so that any oils on your skin aren’t transferred to the dress). And refold it along different lines than it was last folded so that stress tears don’t occur along fold lines.