Risk management - Rather than looking for one big trade, the way a trend trader might, the scalper looks for hundreds of small profits throughout the day. In this process the scalper might also take hundreds of small losses during the same time period. For this reason a scalper must have very strict risk management never allowing a loss to accumulate.
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.