So while the smaller fast growers risk extinction, the larger fast growers risk a rapid devaluation when they begin to falter. - Peter Lynch

Know what you own, and know why you own it

In general, if you polled all the doctors, I’d bet only a small percentage would turn out to be invested in medical stocks, and more would be invested in oil; and if you polled the shoe-store owners, more would be invested in aerospace than in shoes, while the aerospace engineers are more likely to dabble in shoe stocks. Why it is that stock certificates, like grasses, are always greener in somebody else’s pasture I’m not sure.

Find something you enjoy doing and give it everything you've got, and the money will take care of itself.