Investing is fun and exciting, but dangerous if you don't do any work.

When people discover they are no good at baseball or hockey, they put away their bats and their skates and they take up amateur golf or stamp collecting or gardening. But when people discover they are no good at picking stocks, they are likely to continue to do it anyway.

Invest in what you know.

The worst thing you can do is invest in companies you know nothing about. Unfortunately, buying stocks on ignorance is still a popular American pastime.

That's not to say there's no such thing as an overvalued market, but there's no point worrying about it.

Investing in stocks is an art, not a science, and people who've been trained to rigidly quantify everything have a big disadvantage.

Your investor's edge is not something you get from Wall Street experts. It's something you already have. You can outperform the experts if you use your edge by investing in companies or industries you already understand.