Avoid the water heater, or an area that will flood and get a fire liner. Far more guns are burnt up than stolen.

If you're in a home that you'll stay in long enough to lose the safe when you move using concrete fasteners to bolt it into the floor.

These things require a hole to be hammer drilled into the concrete then you tap them in place using a hammer. Drop a couple of flat washers on and then a bolt to tighten everything down. The trouble comes when it's time to move the safe as removing the bolts still leaves the studs sticking up from the floor - you'll have to struggle like crazy to get the safe up above the studs to remove it.

Most safes locks aren't cracked - the science behind the locks is better than most thieves (that's a good thing). They are typically broken into by pounding away at one of the corners until it cracks. Then a cold chisel is worked into the hold and hammered at until enough of the safe is open to allow the thief to stick an arm it and fish out the contents.

Placing the safe into a corner of the basement protects three of the four corners. I also keep mine out of sight and have used a large cardboard box to cover it making it look like an old un-used freezer.