You've heard the advice every time you travel by plane: "Put on your own oxygen mask before helping the person next to you." That tenet holds true for money as well as for oxygen. Should you save someone else's financial life at the expense of your own? Especially when it comes to dealing with adult children, this is a dilemma that seems to be arising more frequently. For instance, should you borrow money from your retirement plan to pay for college? Should you tap your savings for a down payment on a home for the newlyweds? Should you co-sign your daughter's car loan? When you lend money to friends and family, you're asking for trouble. And it's not just the financial consequences if the loan is not repaid and turns into a "gift." It's the emotional issues that arise when you watch your relative buy a new car or take a vacation before the loan is paid off. So whenever I receive an email asking for advice about bailing out a troubled offspring or relative, I immediately take the negative approach. I believe that if a bank won't lend money to your son, daughter, brother or sister, you shouldn't put your own hard-earned dollars on the line. It's a tough analysis, because lending money to a relative isn't a financial decision; it's an emotional one. And with so many people incapable of simply saying no to a relative in need, I believe you should consider carefully the proper way to handle this kind of transaction. It's very important to legally define and document the terms, interest rate and repayment schedule. That simple step can help your own finances and taxes -- as well as your peace of mind.