A scalper intends to take as many small profits as possible, without letting them evaporate. This is the opposite of the "let your profits run" mindset, which attempts to optimize positive trading results by increasing the size of winning trades while letting others reverse. Scalping achieves results by increasing the number of winners and sacrificing the size of the wins. It's not uncommon for a trader with a longer time frame to achieve positive results by winning only half or even less of his or her trades – it's just that the wins are much bigger than the losses. A successful scalper, however, will have a much higher ratio of winning trades versus losing ones, while keeping profits roughly equal or slightly bigger than losses.
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.
As with any other style of trading, many different methods of scalping exist. The most well-known scalping technique is using the market's time and sales to determine when and where to make trades. Scalping using the time and sales is sometimes referred to as tape reading because the time and sales used to be displayed on the old-fashioned ticker tape, known as the tape.
Frequency and costs: A novice scalper has to make sure to keep costs in mind while making trades. Scalping involves numerous trades — as many as hundreds during a trading session. Frequent buying and selling is bound to be costly in terms of commissions, which can shrink the profit. This makes it crucial to choose the right online broker. The broker should not only provide requisites like direct access to markets, but also competitive commissions. And remember, not all brokers allow scalping. 
The problem most new traders make is that they don't practice a strategy in a demo account, for several months or more, before risking real capital. Therefore, they have no idea how a strategy works, and how they need to adjust it when market conditions change. The demo accounts serves as a testing ground, where new traders can test out ideas, see what works and hone trading psychological skills (such as patience, discipline and focus).
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.