It doesn't matter if you're a growth, value, income, or momentum-focused investor -- building a successful investment portfolio takes skill, research, and a little bit of luck.But what's the best way to find the right combination of stocks? Because funding things like your retirement, your kids' college tuition, or your short- and long-term savings goals will definitely require significant returns.Enter the Zacks Rank.What is the Zacks Rank?A unique, proprietary stock-rating model, the Zacks Rank uses earni ...