Although there are some 9,000 publicly-traded companies, the core of your stock portfolio should consist of big, financially strong companies with above-average earnings growth. Surprisingly, there are only about 200 stocks that fit that description, and we narrow down the list even further in the Sivy 100, a collection of our favorites selected by CNNmoney's stock columnist, Michael Sivy. A good stock portfolio should consist of 15 to 20 stocks in at least eight different industries -- but you don't have to buy them all at once.

Since you want to be able to hold your stocks for a long time, they should offer a total return higher than the 12 percent historical market average. You can estimate the likely return by adding the dividend yield to the projected earnings growth rate -- a stock with 11 percent earnings growth and a 2 percent yield could provide a 13 percent annual total return.

As a general rule, stocks with moderately above-average growth rates and reasonable valuations are the best buys. Statistically, high-growth stocks are usually overpriced and have a harder time meeting inflated investor expectations. The first thing to look at is the stock's price/earnings ratio compared with its projected total return. Ideally, the P/E should be less than double the projected return (a P/E of no more than 30 for a stock with 15 percent total return potential).

A well-balanced portfolio might include a couple of industrials (an example might be Boeing) with 9 percent growth rates and 3 percent yields, selling at 17 P/Es. Consumer growth stocks (maybe Wal-Mart) with 13 percent growth rates and 1 percent yields, at 23 P/Es. And perhaps a couple of tech stocks with 25 percent growth rates and 60 P/Es (don't overdo it on those). If you can average a 14 percent return over the next 10 to 20 years, you'll reach your financial goals -- and probably outperform most pros as well.