WEDNESDAY, March 21, 2018 (HealthDay News) -- No one likes to think about end-of-life issues, but it's important for every adult to have a will, no matter their age.

Writing out a will is the first step in what's called estate planning -- how you want your property distributed after you die. If you don't have a will, your estate will go into probate, with the court deciding who gets your assets and even personal belongings.

Here are some general rules for writing a will:

• In most U.S. states, you must be 18 or older.
• A will must be written in sound judgment and mental capacity to be valid.
• The document must clearly state that it is your will.
• You must name an executor, the person who will see to it that your estate is distributed according to your wishes.
• To be valid, you must sign the will in the presence of at least two witnesses.
• It's not necessary, but notarizing or recording your will can safeguard against any claims that it's invalid.

You can write a will yourself if you follow key rules, but you may want to get legal advice in case there are state laws that conflict with your wishes. Having a lawyer may give you more peace of mind, especially when you have children and must name guardians who will raise them. A lawyer will also let you know if you and your spouse should have separate wills.

Review your will from time to time and consider making changes if:

• The value of your assets changes.
• You marry, divorce, remarry or have a(nother) child.
• You move to a different state.
• Your executor dies or becomes incapacitated, or your relationship changes.
• One of your heirs dies.
• The laws affecting your estate change.

Other important documents are called advance directives. These include a living will with instructions on what medical care you do or don't want in the event you're unable to speak for yourself.

If you have a social media presence, you might also write out a statement of how you would like your online identity handled after your death and appoint an online executor who will close your email and social media accounts.

More information

The Family Legal Issues section of USA.gov details what's in a will as well as a power of attorney.