Your employer-sponsored retirement plan is just one leg of the proverbial three-legged stool of a retirement plan.
"One of the largest mistakes is lack of planning in a holistic sense," Hottin says. "People fail to consider their retirement plans as part of the bigger picture. Your employee retirement account should be part of an overall strategy of financial well-being."
In other words, Green says, the term "retirement plan" should refer not just to tax-qualified plans such as IRAs and 401(k)s, but also other sources of income such as Social Security, company pensions, part-time work and other money saved up -- "your overall plan for how you're going to get through the remainder of your life."
Of course, many variables are beyond your control: You don't know how long you will live, how your investments will perform or whether you'll encounter an unforeseen expense that can derail your plans. So the best way to plan for the unexpected is to spend less, invest as much as you can and choose investments wisely.