The first type of scalping is referred to as "market making," whereby a scalper tries to capitalize on the spread by simultaneously posting a bid and an offer for a specific stock. Obviously, this strategy can succeed only on mostly immobile stocks that trade big volumes without any real price changes. This kind of scalping is immensely hard to do successfully, as a trader must compete with market makers for the shares on both bids and offers. Also, the profit is so small that any stock movement against the trader's position warrants a loss exceeding his or her original profit target.
Volatility is the name of the day-trading game. Day traders rely heavily on a stock’s or market’s fluctuations to earn their profits. They like stocks that bounce around a lot throughout the day, whatever the cause: a good or bad earnings report, positive or negative news, or just general market sentiment. They also like highly liquid stocks, ones that allow them to move in and out of a position without much affecting the stock’s price.

The profit potential of day trading is perhaps one of the most debated and misunderstood topics on Wall Street. Internet day trading scams have lured amateurs by promising enormous returns in a short period. The idea that this kind of trading is a get-rich-quick scheme persists. Some people day trade without sufficient knowledge. But there are day traders who make a successful living despite—or perhaps because of—the risks.
Assess how much capital you're willing to risk on each trade. Many successful day traders risk less than 1% to 2% of their account per trade. If you have a $40,000 trading account and are willing to risk 0.5% of your capital on each trade, your maximum loss per trade is $200 (0.005 x $40,000). Set aside a surplus amount of funds you can trade with and you're prepared to lose. Remember, it may or may not happen.