Most desireable to more desireable to desireable:
1: Physical bullion gold, silver, and palladium in coin or bar, without numismatic added value
2: The same as 1: except including coins with numismatic value
3: Gold ETF, (GLD), or silver ETF, (SLV). There are other precious metal ETFs and they are fine.
4: Bullionvault.com or goldmoney.com
5: pool account at kitco or Perth mint
Do not buy mining or precious metal stocks unless you know how to invest in precious metal stocks and you absolutely know that the odds are that you will lose money in precious metal stocks.
Do not buy leveraged futures no matter what you think you know.