LIFE IS FULL of surprises some welcome and some, well, not. Whether your dog bites a neighbor or you get hit by a bus, you need to be prepared for your family's sake.

Many people with the best of intentions don't know where to start. Here's a list of five crucial documents to help you prepare for the unexpected.

1. Medical Directive

Medical directives, also known as advanced-care directives, aren't only for people over age 50. Anyone who wants his wishes carried out in the event that he can't communicate with a doctor should sign one. Like it or not, even healthy young people aren't immune to devastating accidents.

A medical directive refers to two documents: a living will and a medical health-care proxy. A living will informs a physician how you wish to receive care in different situations. In the event that an accident leaves you with no brain activity, for example, you might decide not to receive nutrients that would keep you alive.

A medical health-care proxy names a surrogate, such as a spouse or parent, who can make decisions on your behalf. Without this, family members could argue over who has your best interests in mind.

Advanced-care directives, unlike many other legal documents, don't require you to seek the help of lawyers. You can download free forms from the Caring Connections web site or others. In most states, you'll need a witness, and some states also require the document to be notarized. Then, you should simply make sure it's filed away in a safe place and can be found in the event of an emergency. If you have a regular doctor, ask that a copy be placed with your medical records.

2. Will

What happens if you die before making a will? The court will assign an administrator to divide your assets according to state laws. This could prove particularly troubling for families with small children.

In some states, such as Georgia and Florida, assets are split equally among the surviving spouse and children. This could leave a parent strapped for cash, since the children's money is often put into trust until they reach a certain age.

A will is also the document in which parents name guardians for their children. If both spouses die with no will, the court will appoint a guardian -- yet another reason to draft a document as soon as possible.

Even single people can benefit from a will. Without one, the state is likely to decide that your parents receive your assets, even though your sibling might benefit more. (For more on wills, read "Good Will Hunting.")

3. Umbrella Policy

We live in a litigious society. If someone trips on your icy front stoop, there's a good chance he or she will sue you. That's why financial planners recommend their clients purchase an umbrella policy for added liability coverage.

An umbrella policy provides catastrophic liability coverage for your home, auto and other things. There's no exact science to tally how much coverage you need. As a guideline, think about your own net worth and how much coverage you'd need to protect your assets. Remember, if you were sued, a lawyer could go after the equity in your home, your car and all of your financial assets, including your IRA. A $1 million policy should cost between $200 and $300 a year.

There are two things to look for when shopping for a policy. First, make sure you get the full face value of the policy. Watch out for plans that pay only the gap between the original homeowners' or auto policy and the total amount on the umbrella policy. Then, look for what's called drop-down coverage. This means that the umbrella will cover you in situations where your original policies might not.

4. Disability Insurance

Most people receive some disability insurance from their employers. But unless you can afford to live on, say, 60% of your salary, you probably need more. You can buy it either through your employer or on the open market. The idea is to fill in as much of the gap between your employer's plan and your current income as possible.

How much will disability coverage cost? It varies greatly based on health, income, occupation and other factors. Just as an example, a 35-year-old healthy male working at a desk job can pick up a policy for about $45 a year for every $100 a month in coverage. Just make sure you find a policy that promises to pay benefits if you can no longer perform the same type of job. A catastrophic benefit will also provide a little extra income if you're severely disabled and need assistance with what the industry calls activities of daily living, including such tasks as eating and bathing. This feature, however, will cost you a little extra.

5. Life Insurance

As soon as a couple owns a home together, they should buy a term-life policy to cover the cost of the mortgage. Then, when baby makes three, parents should increase the face value. As a general rule, each household breadwinner should carry a policy worth five to 10 times their annual income. (How much life insurance do you need? Use our calculator.)

But even stay-at-home spouses should consider a little coverage. The thinking is that if it would be a financial hardship for the other parent to hire a nanny to take your place, then your economic value should be insured, too. At least until the kids are in school full time.