
Glass ornaments last generations if they're stored right: individual compartments or tissue-wrapped in a sturdy box, never loose in a bag where they can knock against each other.
Hang heavier ornaments on sturdy branches near the trunk, and use proper ornament hooks rather than the thin metal loop they ship with — it distributes weight more evenly and is easier on delicate necks.
Keep ornaments out of direct sun and away from extreme attic heat or damp basements between seasons; consistent, moderate storage does more for longevity than any special cleaning product.