Years ago, when stocks were quoted in fractions, there was a standard spread of 1/16 of a dollar or a "teenie". This spread allowed scalp traders to buy a stock at the bid and immediately sell at the ask. Hence the teenie presented clear entry and exit levels for scalp traders. The scalp trading game took a turn for the worst when the market converted to the decimal system. The decimal system closed the "teenie" often times to within 1 penny for high volume stocks. This overnight shifted the strategy for scalp traders. A scalp trader now had to rely more on their instincts, level II, and the time and sales window.
There are a variety of methodologies to capitalize on market swings. Some traders prefer to trade after the market has confirmed a change of direction and trade with the developing momentum. Others may choose to enter the market on the long side after the market has dropped to the lower band of its price channel—in other words, buying short-term weakness and selling short-term strength. Both approaches can be profitable if implemented with skill and discipline over time.
Day trading was once an activity that was exclusive to financial firms and professional speculators. Many day traders are bank or investment firm employees working as specialists in equity investment and fund management. Day trading gained popularity after the deregulation of commissions in the United States in 1975, the advent of electronic trading platforms in the 1990s, and with the stock price volatility during the dot-com bubble.[2]

Another trading method is known as fading the gap at the open. When the opening price shows a gap from the previous day’s close, taking a position in the opposite direction of the gap is known as fading the gap. For days when there is no news or there are no gaps, early in the morning, day traders will take a view on the general direction of the market. If they expect the market to move up, they would buy securities that exhibit strength when their prices dip.
Spread trading This high-speed technique tries to profit on temporary changes in sentiment, exploiting the difference in the bid-ask price for a stock, also called a spread. For example, if a buyer’s bid price drops suddenly, the day trader might step in to buy and then try to quickly resell at the stock’s ask price or higher, earning a small “spread” on the transaction.
You're probably looking for deals and low prices, but stay away from penny stocks. These stocks are often illiquid, and chances of hitting a jackpot are often bleak. Many stocks trading under $5 a share become de-listed from major stock exchanges and are only tradable over-the-counter (OTC). Unless you see a real opportunity and have done your research, stay clear of these.