After losing a grand total in the dozens of diamonds and diamond implements, countless stacks of iron, gold, lapis, redstone, at least three music disks, perhaps a dozen saddles, dozens of stacks of moss stone and numerous saddles to blundering drunkenly into lava, my wife and I now have a system.
Well... okay not so much a system as an obsessive-compulsive reflex. As soon as we break into any area with significant lava, we dig a safehouse, put down beds and build chests for everything of remote value.
Since then, we've only lost stone.
And two diamond picks.
And another music disk.
And some diamonds.
And everything else.
But less of everything else!