If you are content with low returns then it is probably best to save your money in a low interest account.  It will be insured and is 'safe'.
Gold is a solid investment, the price is quite low at the moment, it seems like a safe long term investment, not very fungible though.

Bitcoin is dangerous, you could lose most of your money quickly, you could also make lots of money. It is fungible, if you can handle the stress of big price swings, it is a good investment in my opinion.

I wouldn't put all my eggs in one basket.  I personally am long oil at the moment, I can ride out the overproduction dip, but it won't stay at $50-60 for long, I am willing to bet on that!