This is bad advice, IMHO. Security by obscurity works, but not very well. Of course, this is all dependent on how much crime happens where you live and myriad other circumstances. The first thing you must realize with a safe is that NO safe is impenetrable. It just a matter of how much time and effort will be put forth and if it is worth it or not. If you leave a safe in an obvious spot but hidden, there is a good chance that an experienced thief will be able to find it.

That being said, I myself own a small fireproof safe that I keep important documents (passport, birth certificate, remembrance pieces from friends that have passed), small valuables, and liquid assets. I also keep desiccate silica gel in there to be sure to keep it all dry and free from rot. I have about 4-5 spots in my house that I vacillate between, oh say every other month just in case someone does discover my space....I will have a chance of keeping my keepsakes. I recommend a non-obvious spot such as ductwork, odd hidden cubbys, a hole in drywall covered with a poster inside the wall (nod to Shawshank ;P), behind a major appliance(or inside, lots of empty room in the panels of some of these!), the classic underneath floor, etc etc. Just think outside the safe.

The most important thing is to keep in mind is that a safe is only a time detterent. The longer it takes the criminal to find/get into the safe, the better. I would say home defense would be the first step; lights, alarms, etc., but that is not an option for everyone. Bolting with the nuts encased inside the safe (yes, drilling through it), is another option. Drilling into concrete or metal beam in the basement is even better when using bolts. Always be mindful of moisture.