Gun safe is a good idea, hide the safe as well though (for example, put it in the corner of a closet and bury it underneath your spare sheets/bedding).
The biggest tip that I can give though, is to not raise any "red flags" that are going to make your home a target to an invader.
Things such as:
- Don't post on Facebook when you are going on vacation.
- Don't post pics taken at your vacation destination with tags like, "enjoying the view!".
- Make sure you always lock your door when you leave.
- Make sure your windows are always locked.
- Keep your garage closed during the day (even if the access door to your home is locked... lots of criminals are hitting up garages these days for powertools and many will try the door as well to see if it opens).
- Never tell ANYONE about your plans to store massive amounts of cash within your house
- Always deadbolt your door when you are going to sleep
- Don't "brag" about upcoming lengthy vacations to people you don't implicitely trust (don't tell co-workers or neighbors you don't know very well)
- When you do go on vacation, invest in light timers so that it gives the appearance that you are at home
- When you are on vacation, have a trusted relative/family member/neighbor (preferably one who doesn't know that there are piles of cash stored all over your house) drive by your house at least every few days just to make sure everything is ok.
- If you have TONS of cash and are legitimately worried, invest in an alarm system.
If you do all these things and your home is still broken into... that's just bad luck. If you hide your safe (and own a good safe) and it's broken into, that's REALLY bad luck and most likely your house wasn't just randomly broke into... it was a targeted burgurly.
End of the day, if someone REALLY wants to get into your house, they are going to be able to do it. Then again though, there are so many idiots out there who make themselves targets, that your average burgler (especailly one that is going to know how to break a top of the line safe) isn't going to randomly kick your door in while you are away and rummage through your house looking for a safe loaded with cash.
That's just my .02 cents on all of this. I'm not saying I'm right or anyone else is wrong, just my opinion.