Retirement mistake #9 is getting married a second time without a prenuptial agreement.

If your first marriage ended in divorce, I suspect I'm preaching to the choir. You now know that you should have had a prenuptial agreement in place for that marriage.

A "prenup" is even more important the second time around. You're worth more. You probably have children who are less than thrilled about your new partner and the effect this relationship could have on their inheritance.

Prenups can protect one spouse when the other is strapped with financial obligations like college tuition, child support, and caring for elderly parents. It can provide that each party will take financial responsibility for the children upon the death of the parent.

A significant benefit of a prenup is that it can limit or waive the other's right to a statutory share of each other's estate.

Don't try to save money by drafting your own prenup. You each need to have experienced legal counsel. Be totally forthright in making full financial disclosure to your spouse. Otherwise, you might find the prenup is not enforceable.

See all ten of the biggest money mistakes a retiree can make.

Dan Solin is the author of the newly published book, The Smartest Retirement Book You'll Ever Read (Perigee Books 2009). His prior books include the New York Times bestsellers, The Smartest Investment Book You'll Ever Read and The Smartest 401(k) Book You'll Ever Read. See SmartestInvestmentBook.com. Read more about Dan Solin.