Day traders use only risk capital which they can afford to lose. Not only does this protect them from financial ruin, but it also helps eliminate emotion from their trading. A large amount of capital is often necessary to capitalize effectively on intraday price movements. Having access to a margin account is also key, since volatile swings can incur margin calls on short notice.
Buying on margin can greatly increase your gains or losses. Brokerages usually allow a bigger margin percentage for a day trading account but reduce the amount of margin available for positions held overnight. Normally a day trading account must have a minimum of $25,000 and can buy on margin at a rate of 4 to 1 giving you $100,000 in buying power, which is called day trader buying power. That number drops to 2 to 1 for positions held overnight, which can be called overnight margin buying power. That means that if you have 100% of your margin being used during the day, you must exit at least half of your positions before the close of the trading day.
In addition to knowledge of basic trading procedures, day traders need to keep up on the latest stock market news and events that affect stocks—the Fed's interest rate plans, the economic outlook, etc. So do your homework. Make a wish list of stocks you'd like to trade and keep yourself informed about the selected companies and general markets. Scan business news and visit reliable financial websites.