Hold no more stocks than you can remain informed on.
There's lots of stocks out there and all you need is a few of 'em. That's been my philosophy.
Behind every stock is a company. Find out what it's doing.
You shouldn't just pick a stock - you should do your homework.
In the long run, it's not just how much money you make that will determine your future prosperity. It's how much of that money you put to work by saving it and investing it.
Never invest in a company without understanding its finances. The biggest losses in stocks come from companies with poor balance sheets.