If you're a long-time reader of SmartMoney.com, chances are you've spent plenty of your free time thinking about the money you'll have available at retirement. But what have you done to plan out your estate? The sad truth is that most of us -- some 70% of adult Americans -- have neglected to write a will. Some think their assets are just too puny to worry about, others worry that the costs of writing a "last will and testament" are too high.

But wills aren't just vehicles for the wealthy or the morbid. If you've got a family and a home -- not to mention a savings account -- you should definitely have one. Cost is no excuse. While the average will drawn up by a lawyer typically runs from $500 to $1,000, you can get a simple will at a legal clinic for as little as $75.

For most people, the first time in your life that a will becomes imperative is when you have children. Forget about your assets for a minute. In the terrible event that you and your spouse die at the same time without a will, it falls to a probate court judge to name a guardian for your minor-aged children -- not a pleasant prospect. That's why it is a crucial first step to name a guardian you can trust. Our experts recommend naming an alternate guardian in the document, as well, in case something happens to your first choice.

Writing a will, of course, is also your chance to clarify who gets what in your estate. Before you can do that, however, you have to tally up your assets. That includes your house, your investment portfolio, the value of your retirement plan and the payout of your insurance plan. If the experience of our experts is any guide, most people are worth more than they think. Once you've got your assets listed, you can decide what you want to leave to whom and who will be executor of your estate. One important caveat: Make sure that the beneficiaries listed in your will match the beneficiaries you name on your insurance policy and in your 401(k).

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Once you have a will in place, don't forget to update it regularly. You'll need to amend it whenever there is a big change in your family's circumstances -- a birth, a death or marriage, or even if you move out of state. Again, our Estate Planning section has more tips on setting up one of these crucial documents as cheaply as possible. But do it now. A will may seem like a hassle, but that's nothing compared to the troubles your heirs will endure if you are unfortunate enough to die without one.