Prior to investing you should...
Draw a personal financial roadmap.
Evaluate your comfort zone and the risks you are taking.
Consider an appropiate mix of investments
Be careful of investing heavily in shares of employer's stock or any individual stock.
Create and maintain an emergency fund.
Pay off high interest credit card debt.
Consider dollar cost averaging.
Take advantage of free money from employer.
Consider rebalancing portfolio ocassionally.
Avoid circumstances that can lead to fraud.