Preservation has moved way beyond preventing mothballs. So, whether you're planning to pass down a christening gown or share family photographs, get the facts about how to keep them as pristine as possible. After all, a hope chest rotting away in a damp basement isn't going to prompt an outpouring of special memories for anyone.
Besides moisture, direct sunlight is the biggest threat to your heirlooms. Everything -- from fabrics and papers to wooden furniture and photographs -- can be damaged by sunny conditions. Your best bet is some middle-of-the-road climate control. Avoiding too much heat or cold, as well as excess of dampness or dryness, can go a long way toward preserving keepsakes for posterity.
Speaking of future generations, don't feel like you have to save everything, a la packrat. Sometimes setting aside fewer items makes them more special. Plus, your kids will someday thank you for denying them what's become a too-oft rite of passage: Going through mom's things. And by "things," we mean all that junk you've stored away for "someday."