When Kimberly Rizy's father asked her whether she would be the executor and trustee of his estate, she agreed without skipping a beat. But after he died in 2003, Ms. Rizy, age 40, of Westport, Conn., wished she hadn't taken the matter so lightly.

"It was more than a full-time job for the first seven months," says Ms. Rizy, who learned that her father had 32 properties and investments in eight states, as well as two corporations.

She couldn't locate the deeds to most of the properties, and faced managing some properties encumbered with environmental problems. Her sales and marketing background didn't fully prepare her for the many real-estate, investing, accounting and legal issues she had to deal with. Even now, with the estate having paid more than $100,000 in legal, accounting and appraising fees, Ms. Rizy is still working with 13 lawyers in various states trying to sort out her father's affairs and distribute his assets.

Executors and trustees are often caught off guard by the extent of their responsibilities. "People don't understand the burden they're taking on until it's too late," says Sidney Kess, an estate-planning lawyer in New York. And by that time, they not only face mountains of work, but also are legally responsible for handling the estate properly. "You can be personally sued for mistakes," Mr. Kess says.

While an executor and trustee have different responsibilities, one person often serves both roles.

An executor's job begins once the will is read and ends after the estate has been distributed or is transferred to a trust. It involves locating all bank and investment accounts, deeds to properties and other assets. Then, an executor must retitle or sell assets, appraise property, make sure insurance issues are settled, terminate leases, settle debts and expenses, and file income and estate-tax returns.

A trustee's role is to oversee assets in a trust. This typically means investing in beneficiaries' best interests, and distributing assets according to the trust's instructions.

"This can be a lifelong responsibility," says William H. Forsyth Jr., senior fiduciary counsel and managing director at Bessemer Trust in New York.

Theoretically, the task should be fairly straightforward because wishes are spelled out in the trust. But it's not always so. Trustees may face challenges from contentious beneficiaries, and they often face tough investing decisions. For example, the surviving spouse may want assets invested to throw off as much income as possible, while secondary beneficiaries usually favor investing for growth so they have more to inherit in years to come.

What's more, trustees often have the enormous responsibility of deciding when to make payouts to beneficiaries.

"This authority can get more complicated when there are problem beneficiaries -- someone with a substance-abuse problem, for example," says Charles Aulino, director of financial planning at Glenmede Trust Co. in Philadelphia.

Before accepting either title, make sure you're up to the task. It takes a highly organized person to get the job done right, Mr. Aulino says. And realize, too, that it's not just an administrative position.

"Emotions come up in a huge way in families," Mr. Forsyth says. "I've seen beneficiaries going to court over who is going to get their parents' $15 etching."

However, whether you are appointed executor, trustee or both, there are ways to avoid complications, especially if you act before the grantor's death. Here are a half-dozen steps to make your fiduciary responsibilities easier:

ASK FOR A ROAD MAP OF THE ESTATE.
A will tells you who will be inheriting assets, but it doesn't necessarily identify all the assets or tell you where to find them. This can be an enormous headache for the executor, especially if records are disorganized and there are multiple investment accounts or real-estate holdings.

To avoid frustration, request that a special document be included in the will that catalogs all accounts, debts, assets, benefits and insurance policies. It should list account numbers as well as phone numbers of contacts for each account. And it should explain where documents are located.

"There's no standard form for this, and it's not a legal document," says Lisa Osofsky, an accountant at Weiser LLP in New York. "But it will make your life as executor a whole lot easier."

OUTSOURCE WHAT YOU CAN'T HANDLE.
Don't plan on doing everything yourself. "You have a fiduciary responsibility to handle things the best you can, and in many cases this means having a professional take on certain tasks," Ms. Osofsky says.

There are a couple of ways to accomplish this. Either suggest that a co-executor or co-trustee be named who is qualified in trust and estate law, such as an attorney or accountant.

Or, plan on hiring help yourself. Discuss with the person appointing you as executor or trustee which professionals he or she currently works with. "Those are probably the best to hire after death, because they'll be familiar with the circumstances," Mr. Forsyth says.

CREATE A TIMELINE.
There are a number of important deadlines that an executor or trustee must meet. "If you know what they are, you can work toward them well in advance," Mr. Forsyth says.

Among the key deadlines for executors: Estate taxes must be filed within nine months of the date of death, or 15 months with a tax-filing extension. "You have to start selling assets early on so you have cash to pay taxes," Mr. Forsyth says.

Trustees and executors must pay attention to state deadlines, too. For example, each state has deadlines by which the estate must pay cash legacies to beneficiaries, or interest will be owed. In New York, beneficiaries must be paid within seven months of the benefactor's death.

PREVENT PROBLEMS WITH BENEFICIARIES.
To avoid a court battle between beneficiaries over tangible property, ask the person writing the will to include a letter to the beneficiaries in his or her handwriting, specifying who gets Grandpa's portrait, Grandma's ruby ring and other prized possessions.

As for everything else, the letter should order that if it isn't divvied up within three or four months, the executor should sell it.

"The personal touch often convinces beneficiaries that this is what their mom or dad truly wanted," Mr. Forsyth says.

If you have been asked to be a trustee with the authority to distribute assets as you see fit, get specific guidance. Ask the grantor to write down specific circumstances under which the beneficiaries should receive cash, such as for education, a down payment on a house or a wedding.

TREAT YOUR ROLE AS A JOB.
One of the biggest mistakes that people make when they're asked to serve as executor or trustee is to insist that they do it as a favor, Mr. Forsyth says. "Don't refuse payment," he says. "This is a business matter and should be treated that way. Otherwise it doesn't become a priority."

How much you are paid depends on your state. For executors, typically it's calculated as a percentage of assets in the estate. For example, in New York, you get 5 percent of the first $100,000, 4 percent of the next $200,000, 3 percent on the next $700,000, 2.5 percent on the next $4 million and 2 percent on anything more.

Trustees are paid according to a similar schedule, but receive an annual commission rather than a one-time payment.

MAINTAIN DETAILED FILES.
Keep notes on all the decisions you make, hours you spend, and expenses paid on behalf of the estate. "No matter how many lawyers or accountants or other professionals you hire, as executor or trustee you're still ultimately responsible for the proper handling of an estate," Ms. Osofsky says.

As long as you can show that you have done your best to maintain the best interests of the estate, you will be prepared for the day when a disgruntled beneficiary accuses you of neglecting your responsibilities.