Commissions for direct-access brokers are calculated based on volume. The more shares traded, the cheaper the commission. The average commission per trade is roughly $5 per round trip (getting in and out of a position). While a retail broker might charge $7 or more per trade regardless of the trade size, a typical direct-access broker may charge anywhere from $0.01 to $0.0002 per share traded (from $10 down to $.20 per 1000 shares), or $0.25 per futures contract. A scalper can cover such costs with even a minimal gain.
The first EMA (50) must be positioned above the second EMA (100). When this has occurred, it is essential to wait until the price comes back to the EMAs. In turn, the Stochastic Oscillator is exploited to cross over the 20 level from below. The moment you observe the three items arranged in the proper way, opening a long (buy) order may be an option.
Some of the common mistakes that scalpers make are poor execution, poor strategy, not taking stop-losses, over-leveraging, late entries, late exits and overtrading. Scalping generates heavy commissions due to the high number of transactions. A per-share commission pricing structure is beneficial to scalpers, especially for those who tend to scale smaller pieces in and out of positions.
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.