As with anything else, people make mistakes drafting wills. While the subject of wills and estates is a matter of state law, thus having differing rules from jurisdiction to jurisdiction, there are some general rules and some rules that apply to most jurisdictions. Here are seven generally-applicable mistakes to avoid in drafting a will:

The biggest mistake most people who have a will make is not keeping it updated. Amendments, known as 'codicils,' need to be added to a will when another child is born (or dies), or some other significant change occurs.

For example, if you have a will, then inherit family assets, you may want specific assets to go to specific children. You may want your daughter to have your mother's engagement ring, or a son to have Dad's car.

You may have a will before a child is born, and then things can be messed up because you left your car to Johnny, the house to Phyllis, the business to Roseann, and the will is silent as to Julie, since she was born after it was written. On the other hand, if Roseann predeceases you, you will have missed the opportunity to ensure that the business goes where you want it.

Another mistake is to use an improper format. About half the states allow a hand-written will that you have signed to be considered a valid will. Modern America lends itself to people generating documents on a computer and printing them out, but THIS IS NOT HAND-WRITTEN. Called a 'holographic will,' it MUST be written by hand by the person making his or her will and signed and dated.

Remember that the primary purpose of a will is to show how you want to dispose of property. One mistake some people make is writing a document that is little more than a tirade against some potential inheritor. A valid will MUST indicate that you intend for this document to be your final word on how you want your property distributed.

A will typically must be witnessed, and the rules vary from state to state. A common misconception is that a will must be notarized, but that is not true. When you have your will notarized, and not signed by witnesses, the notary seal does not make it a valid will.

Yet another mistake people make is having their will witnessed by people who will inherit under the will. In most states, witnesses are not allowed to inherit under the will. This is designed to avoid undue influence on a person writing his or her will, and is something to avoid in all states. Remember, they are ONLY witnesses to the fact that you signed your will, NOT to anything in it.

If you have minor children, please remember that they will need more than money if you die. In addition to disposing of property, you have made a mistake if your will fails to appoint a guardian for them, if there is no surviving parent. Otherwise they could have all your money, but end up wherever the court puts them.

Finally, people tend to take what they have heard on television about wills or from a relative in another state and slap one together. Find out what the laws are in your state and follow them, because requirements do differ. For example, Vermont requires three witnesses to a will; Mississippi requires two.

Another example of state differences is in age requirements. In most states you must be 18 to make a will, but not all. If this is an issue, check it out first several web sites have information on wills by state, so use Google or Yahoo to look.

If you have a substantial estate, it would be worthwhile to hire an attorney to draft your will, because he or she should be familiar enough with the applicable laws to ensure that what you want to happen is what actually happens after you die. After all, isn't that really why you have a will?