Facebook goes public May 18 at $28-$35 a share

With roughly 338 million shares being sold, that would value the company at between $77 billion and $96 billion. "Some people will buy Facebook stock no matter what -- they'll just buy it," Francis Gaskins, president of Marina del Rey-based researcher IPOdesktop.com tells Bloomberg. Yeah, but is that such a great idea? Smart Money's Jack Hough has some advice for potential shareholders:

1. Don't buy at the open. Popular dotcom IPOs in from recent years-LinkedIn, Groupon, Zynga closed lower than they opened on their first day. One past exception is Google, but it closed only fractionally higher and at one point during its first day traded 4% below its opening price. Also, Google used a non-traditional IPO method called a Dutch auction, which tends to cut down on frantic price swings during early trading.

2. Use a "limit" order. After waiting for the open, those who buy should consider specifying a maximum price. Feel free to set it below the opening price. If it doesn't get executed, you can always change it to a "market" order for immediate execution shortly before the close of trading.

3. Bet small. Don't be swayed by Wall Street projections for how much Facebook could be worth five or 10 years from now. Valuation math is best used to help determine which stocks are good deals based on today's results or near-term forecasts. For example, Apple, Google, Microsoft and Intel look reasonably priced relative to recent earnings, sales and cash flow. But projections for how much companies will earn in 2018 amount to guessing. After all, even over the past quarter, analysts have been exactly right about earnings estimates for fewer than 10% of S&P 500 companies.