(MONEY Magazine) – When it comes to a will, all too many people act as if they'll get around to drafting it sometime soon -- just before they die. Like stock market timers, however, they forget one important thing: death, as well as market turns, has a way of happening when least expected. Consider the consequences of dying without a will: The state will select your heirs. Should you die intestate -- meaning with no will -- the courts will gladly step in and put your personal affairs in order. But the law's notion of who gets what after you're gone probably doesn't match your own. In most states, your property will be split among your spouse and children, often with one-half to two-thirds going to your offspring. Without a single stroke of your pen, you could be assuring your mate's impoverished old age. A probate court judge will name a guardian for your minor children. The court will have to look out for your children's welfare because you neglected to do so. You may leave an unnecessarily large bequest to the tax collector. When a will is part of a carefully drawn estate plan that includes trusts, a married couple can pass as much as $1.2 million to their heirs free of federal estate tax. The state will charge you for its services, such as they are. Only in a will can you nominate an executor to inventory your estate, pay your debts, file income and estate-tax returns and distribute your assets to your heirs. If you perish without making such provisions, a judge may tap a public administrator for the task. Allowing the state to settle your estate can be like putting a drunk in charge of your wine cellar. For example, New York's attorney general and its controller uncovered dozens of cases of incompetence and corruption in a 1987 investigation of that state's public administrators. Astonishingly, the public administrator's office of New York County had yet to disburse the $15,000 estate of a sailor lost at sea 31 years earlier. The last correspondence in the government's file, which was from an attorney representing the seaman's son, was 22 years old. Executors, like public administrators, are entitled to fees, which may be set by state law or the probate court. In Mississippi, for instance, an . executor's commission may not exceed 7% of a gross estate. If you name a family member or friend to do the job, he or she may waive the fee. Clearly, a will should be the foundation on which you build your estate plan, unless you use a revocable living trust as a substitute. Unlike wills, such trusts aren't subject to probate. A living trust is not for everyone, though, because the lawyer's fee for drawing one up typically runs to $1,000, vs. a high of around $250 for a simple will. In addition, you must transfer title of your assets to your trust. Attorney Denis Clifford, author of Plan Your Estate (Nolo Press, $17.95), advises young people who are unlikely to die for many years to write wills, then after they've accumulated more property and are closer to death, revise their estate plans to include revocable living trusts. Even if you establish a revocable living trust, you will still need a pour-over will, which stipulates that any assets you neglected to place in your living trust will go there after your death. To learn more about living trusts, see ''Trusts That Protect Your Family'' on page 110. Before you begin to set down your wishes in a will, however, you should know that the law doesn't give you free rein to disinherit your spouse. In the 41 common-law states, for instance, your spouse is entitled to a portion, usually a third, of your estate. As a result, the most effective way to disinherit your spouse is by getting him or her to sign a prenuptial or nuptial agreement to that effect. If you live in one of the nine community property states (Arizona, California, Idaho, Louisiana, Nevada, New Mexico, Texas, Washington and Wisconsin), you can leave your half of the community property and all of your separate property to whomever you please. In Louisiana, you cannot disinherit your children. Indeed, cutting your offspring out of your will is tricky in most states because the law considers your children to be the ''natural objects of your bounty.'' So if you fail to mention a wayward son in your will, he could contest its validity by claiming that you were incompetent when you wrote it. To avoid litigation, it's wise to state in your will: ''I make no provision for my son so-and-so.'' That statement shows that you considered your son while writing your will and consciously decided to leave him out. People who plan to use their wills to hurl a final round of insults at family members and former friends who have wronged them should find another , outlet for their frustrations. If you refer to your kid sister in your will as a lazy lummox who is unworthy of an inheritance, for example, she could sue your estate for libel. When making bequests, it's generally best to leave percentages of your estate rather than fixed dollar amounts to your heirs because your assets may shrink or swell over the years. You may, however, wish to earmark specific sums for distant relatives, charities or your household help. Remember that you cannot use your will to bequeath property that is jointly held -- your share goes to your co-owner -- or that has a named beneficiary, as does an Individual Retirement Account or life insurance policy. You should list contingent beneficiaries in your will in case your first choices die before you do, cannot be located or refuse to accept your bequests. Says J. Chrys Dougherty, a partner in the Austin, Texas law firm Graves Dougherty Hearon & Moody: ''By naming your church, Harvard or the Salvation Army as your contingent beneficiary, you're assured of making a complete disposition of your estate even if everyone you ever gave a damn about goes before you do.'' Don't catalogue everything you own in your will, because your holdings will change. Instead, inventory your assets and list their whereabouts in a separate letter of instruction that you give to your executor and loved ones. In that letter, which generally isn't legally binding, you can also convey your wishes regarding organ donation and funeral services. Many people are tempted to save the lawyer's fees by drafting their own wills. The temptation rises further at the sight of how-to books, software or even blank statutory wills, which are available from state legislatures, bar associations and office-supply stores in California, Maine, Michigan and Wisconsin. (Other states have not passed laws yet authorizing the use of statutory wills.) It's best to resist any such impulse because you run the risk of having a sloppy do-it-yourself will that may be contested by heirs who are confused by its provisions. Besides, statutory wills cannot be customized to fit your particular needs. Michigan's version, for example, doesn't allow you to create a trust. Says Theodore E. Hughes, a Michigan assistant attorney general and author of A Family Guide to Wills, Funerals & Probate (Scribners, $13.95): ''A statutory will is a good stopgap for someone who's planning to see a lawyer next month about writing a will but is getting on a plane to Europe tomorrow.'' Once you have written a will, store it somewhere that's safe from fire and other calamities. Your bank safe-deposit box is a suitable choice only if state law permits your survivors to retrieve your will from your box immediately after your death. In some states, banks must seal safe-deposit boxes at death and can't open them without a court order or without the presence of a state tax collector. If that's the case in your state, leave your will in a depository provided by some probate courts or with your lawyer, who should store it with other wills in a bank vault. Don't forget about your will after you have put it away. Some provisions in the document may become invalid if you marry or divorce. You may also have to amend it if you move to another state or grow considerably richer or poorer. But you needn't throw out your will to make minor changes. You can add or remove a beneficiary, change the amount of a bequest or replace an executor or guardian by asking your attorney to add an amendment to your will called a codicil. Youth alone is no excuse to put will writing off. Dr. Sondi Waters, 28, and her husband Al, 27, have already written complex wills. They particularly wanted to take care of Al's seven-year-old daughter from a previous marriage and protect their million-dollar assets, which include a condominium in downtown Atlanta, more than 30 acres of undeveloped land, an office building in Arlington, Va. and a four-unit apartment house in Chicago. Under the terms of Sondi's will, all of her assets will go to Al. If Al dies first, all of his property will pass to Sondi with the exception of $100,000 that will go into a trust for his daughter Kandace. If the Waters perish together, their property will be divided among Kandace, Al's mother and sister and Sondi's brother and three cousins. Says Al: ''This is our first will, and we plan to review it every two years and revise it as necessary when our personal and financial circumstances change.''