Go to any investment manager and ask them for the secret of investing and they'll tell you, it's really very simple. Diversification. You want to have your money in a spread of things, not just in one idea, market or place.
One of the places you do want to be is in precious metals, the reason being that these are traditionally a hedge against inflation. While some of them (platinum, palladium and even more so rhodium and osmium) are really not for investors, rather they are for speculators, it's is true that a wise investor might have either gold or silver in their portfolio. These have traditionally moved counter-cyclically to other assets, especially those (like bonds) that can be badly damaged by inflation.
But this then brings us on to which, if any, of the various forms of the metals that you should look at. Futures and options are really rather risky for the private investor, and bullion comes in very large chunks (the standard gold bullion bar is 14 kg for example, over $300,000 worth) so probably the best way to gain exposure to the market is to buy gold coins.
Click through the link there and you'll find the Monex Deposit Company who can help you with the details of all of this area of investing.