At four years and counting, the low-yield environment for bond looks likely to continue well beyond 2012 and has caused many investors to sit on the sidelines and miss out on additional income, according to Kathy Jones, vice president and fixed income strategist for the Schwab Center for Financial Research.

"It used to be that you would buy a maturity and forget it, but it's a little more complex than that," says Jones, who has authored a new research paper on the subject. "It's just a more challenging world of bonds these days."

She recommends a strategy that combines laddering bond investments as a way to benefit any upside from interest rate shifts without trying to time them. A mix of essential services bonds, especially those in water and sewage, is a good addition because their yields are outpacing Treasuries, she adds.

"Nominal muni yields are greater than yields on Treasuries of comparable maturities," Jones writes in the paper. "[We] believe that bankruptcies of municipal governments will remain relatively infrequent events. . We generally suggest that muni investors stick to issuers with local economies that are rebounding and management that shows signs of making cuts when necessary."

In addition, about 20% of any bond portfolio should be in a combination of higher risk emerging market bonds, corporate bonds, multi-sector bond funds and preferred securities, Jones writes in the paper.

However, many planners and investors may find the challenge of managing such a complex portfolio daunting to research and maintain. "An alternative to that is to find a managed solution," Jones says. "Those can be complicated credits to look at. Our concern is that people may not appreciate the risk they are taking."

Ann Marsh writes for Financial Planning.