Buying on the bid and selling on the ask. In a very real way, this is Wall Street's equivalent of being on the dealer's side of the blackjack table. That is the only way to consistently make a living at this game. I also hope that people will begin to see that profitable day trading has absolutely nothing to do with traditional investing. Using charts, graphs, and research and reading The Wall Street Journal cover to cover each morning will not help you one bit as a day trader.
News is old the second it goes to print and market conditions can change in the blink of an eye.
You have to be ahead of the curve, not behind it. The window of opportunity in some stocks may sometimes last only a few seconds. This may mean buying a stock and reselling it literally seconds later if you hope to make a profit on the trade. Essentially, you are looking to anticipate and exploit tiny supply and demand imbalances that occur throughout the trading day. It is these small profits of sixteenths, eighths, and quarters that can literally add up to thousands of dollars per day.