Whether 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 how do you find the right combination of stocks? Funding your retirement, your kids' college tuition, or your short- and long-term savings goals certainly requires significant returns.Enter the Zacks Rank.What is the Zacks Rank?The Zacks Rank is a unique, proprietary stock-rating model that utilizes earnings estimate revisions to help investors ...