Scalpers need to be disciplined and need to stick to their trading regimen very closely. Any decision that needs to be made should be done so with certainty. But scalpers should also be very flexible, because market conditions are very fluid and if a trade isn't going as expected, they'll need to fix the situation as quickly as possible without incurring too much of a loss.
Each type of trading has its advantages and disadvantages. The appeal of swing trading is that it provides plenty of opportunities to trade; the dollar risk per trade is lower than with trend trading because of closer stops; it provides greater profit opportunity per trade than day trading; and quick rewards provide emotional satisfaction. The downside of swing trading is that you must work hard all the time to manage trades; you are quite likely to miss major moves where huge profits can be made; and frequent trading results in higher commission costs.
Smaller moves, easier to obtain - A change in price results from imbalance of buying and selling powers. Most of the time within a day, prices stay stable, moving within a small range. This means neither buying nor selling power control the situation. There are only a few times which price moves towards one direction, i.e. either buying or selling power controls the situation. It requires bigger imbalances for bigger price changes. It is what scalpers look for - capturing smaller moves which happen most of the time, as opposed to larger ones.
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.