"One of the most common mistakes people make with regard to life insurance is assuming that their lives aren't going to change, and so they plan for a short time horizon on the insurance front," said Thomas Henske, a certified financial planner and partner at Lenox Advisors.
By midlife, many people are in the throes of raising children and paying off mortgages and may want higher levels of coverage but have difficulty getting it. "Sometimes as we get older, we lose our insurability because we are no longer as healthy or we can only get the coverage we want at an exorbitant price," said Henske, who is also a chartered life underwriter.
Read MoreDon't forget these financial documents
The first issue to consider when it comes to life insurance is whether you need it at all. According to financial advisors, the answer to that question hinges in large part on whether your death would create a financial hardship for a surviving spouse and any children in terms of lost income.
"If someone else depends on your stream of income, then it makes sense to consider life insurance," said Charles Sachs, a CFP and principal at Private Wealth Counsel.
One of the biggest mistakes some married couples make is insuring one partner, the primary breadwinner, and not the spouse who has stepped back from his or her career to take care of children. That can be a costly mistake if the stay-at-home parent dies, advisors say. Among other issues, the surviving parent may face much higher child-care expenses.