Plenty of otherwise intelligent people do boneheaded things with their money, from missing out on opportunities because they're trying to perfectly time the market, to taking financial advice from the wrong people.

Jill Schlesinger, a former financial planner and the author of "The Dumb Things Smart People Do With Their Money," says that most of these errors arise from one of two emotions that can override our intelligence -- fear or greed. She sat down with TheStreet to discuss the most common financial mistakes, why we make them and how we can overcome them.

Related. Your Single Most Important Financial Decision

Gen Xers, You Want To Take Care of Your Finances? Be Selfish