Every novice trader should simulate their stock trading BEFORE putting real money down.  This is because most new trader's lose -- that's called "paying tuition to the market."

In addition, if you are in a trading "slump" and losing consistently, I recommend backing off and trading a simulated account until you get your mojo back.

Finally, I recommend that EVERY business executive trade a mock portfolio in which every week, you take your whole portfolio and go long or short the S&P 500 Index using the exchange-traded fund SPY.  I recommend this because the stock market is an excellent leading indicator of the business cycle.  If you as an executive are consistently losing money on this mock portfolio exercise, you are probably going to misread the economy and cost your company a ton of money!

For all of these purposes, I strongly recommend Wall Street Survivor!