To offset this, day traders are often offered the "opportunity" to leverage their portfolios with more margin, four times the buying power rather than double. Taking larger leveraged positions can increase percentage gains to offset costs. The problem is that no one is right all the time. A lack of focus, discipline, or just plain bad luck can lead to a trade that goes against you in a big way. A bad trade, or string of bad trades, can blow up your account, where the loss to the portfolio is so great the chances of recovery are slim. For a swing trader, a string of losses or a big loss can still have a dramatic effect, but the lower leverage reduces the likelihood that the results wipe out your portfolio.

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.

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.