When we talk about "asset allocation," we are, broadly speaking, referring to where you're investing your money. Over longer periods, the more willing you are to take some risks with your money in the stock market, the better your returns will be.

One definition of a worry-free retirement is not having to worry about where the money is coming from. As I have written before, "You are truly retired (or able to retire) when your passive income covers your expenses."

For the more adventurous, real estate income is another way. Investing in rental property can be a compelling option for those who have the time, the handyman abilities, and the willingness to find and work with tenants.

If you're retired, or close to it, you probably know the story. Income--especially guaranteed income--is hard to come by these days. 10-year treasuries yielded 2.3% at the end of November of this year. Ten years ago, that number was nearly double, at 4.5%; 20 years ago, it was 6.1%.

A solid plan for any project, not just retirement, needs strategies to make it happen. Here are some essential building blocks for a retirement plan.