What you pay for an investment is the single biggest determinant for how successful that investment will be. When equity prices are high, your returns will be lower. When they are cheap, your returns will be higher.

Commissions add up, taxes are a big drag, margin ain't cheap. A good accountant costs money as well. The math on this one is obvious, yet investors often fail to recognize it: Keep your costs low and your turnover lower, and you will win in the end.

Hedge funds are not especially liquid. Many are 'gated' - meaning there are only small windows when you can withdraw your money. They typically have a high minimum investment and often require investors keep their money in the fund for at least one year.

In the investment business, you must expect to be wrong.

How are the cabs in your city? In Manhattan, where I work, they are rather awful.

'Returnless risk' is not how you prepare for a decent retirement.