The easiest way to buy gold is through the NYSE listed stock, the ETF, symbol GLD. It tracks the price of gold instantly.
If you want to buy bullion or coins, either gold or silver, make sure you deal with a reputable firm. Search for one at www.Money.org, the website of the American Numismatic Association.
There are also many mutual funds and ETFs that buy only the shares of mining companies. The advantage is that many pay dividends.