Find companies with low long-term debt, enough liquidity to pay their current debts, reasonable margins, and steadily increasing revenue. (E.g. Google, Nucor Steel, Borders Group, Industrial Services of America) Make sure their stock price isn't outlandishly high with respect to revenue and earnings. (E.g. not Google). Buy the rest. Diversify to ensure that, if one company's run by scumbags like Lay and Skilling, you won't lose everything. Every month, review your holdings to make sure nothing in the fundamentals has changed.
That's NOT hard.