Economic uncertainty is causing financial worries worldwide. The Dow plunged 513 points Thursday over fears of a double dip recession, and the European Central Bank has stepped in to calm markets across the Atlantic. With financial fluctuation in the air, what's an average investor to do? Hoard gold bars? Buy a share of Apple stock? Liz Weston author of "The 10 Commandments of Money: Survive and Thrive in the New Economy," guides us through the options.