What are the best pieces of advice to help guarantee a more financially secure retirement?

Prudential Financial's new "Achieving Retirement Security in an Age of Uncertainty," written by Christine Marcks, the president of Prudential Retirement, suggests three straightforward moves: bringing back guaranteed but flexibile income, improve investing and saving behavior and optimizing Social Security decisions.

Retirement, Marcks notes, is a much tricker proposition than it was more than a decade ago. The National Retirement Risk Index, created by the Center for Retirement Research at Boston College, suggests workers face 50-50 odds of not being able to maintain their pre-retirement standard of living, a number that was just 30 percent back in 1989.