Typical things notaries do wrong.
Notaries do many things incorrectly, particalar inexperienced, or unschooled notaries.  Clients will ask you to do all sorts of things.  Some things are merely unorthodox, while others are purely illegal.  Here are some things that notaries do wrong.
 
Copies of vital records
From time to time, a notary is asked to notarize a certified copy of a vital record such as a birth certificate, marriage or death certificate.  This is not legal, and not recommended.  It is legal, but not recommended to do what is called a copy certification by document custodian. This notary act is a glorified Jurat, where the individual who is in charge of the document swears to the authenticity of a copy of the document. 
 
Going to hospitals and jails without asking the right questions.
Many notaries don’t want to go to hospitals and jails because they are afraid.  There is nothing to be afraid of, but there are pitfalls.  Many signers in hospitals are elderly and don’t have ID.  Inmates NEVER have ID.  So, the notary must first be sure the signer or their family members / associates have their ID and it is wise to have them read the ID# and expiration date to the notary, so the notary can be sure that they really have the ID and that its current.
 
Leaving seals and journals unattended.
As a notary public, you and only you are responsible for safeguarding your seal and journal.  Even if your boss or co-workers want to use your seal or inspect your journal, its completely illegal. Only the notary can do a journal query, or use their seal.   Carelessly leaving your seal in an unlocked area is also a very serious notary error.  Seals and journals must always be kept under lock and key.
 
Not having the signer present.
Its common for a client to request that a notary notarize a document when the signer is not around. This is completely illegal.  The signer must be  in front of the notary during a signing.  This means within a few feet and able to communicate directly with the notary.
 
Having an interpreter
Many immigrant families have older members who don’t speak English.  They often attend to their business with their children along to explain things and translate.  When they call the notary over, they often don’t explain that the signer can not speak English, since its not a problem due to the fact that they can translate. But, the notary must be able to communicate directly with the signer.  If the signer only speaks Uzbek, and the notary doesn’t speak Uzbek, then the signing is off.   On the other hand, if the document is in Chinese, and the notary only speaks English, that is okay, since the notary is not liable for the contents of the document.
 
Overcharging
The maximum notary fees vary from state to state.  California and Florida are  “generous” offering $10 per acknolwedged signature, while many other states offer as low as 25 cents or two dollars per signature which is hardly enough to make a living.  It is tempting for notaries to charge more than they are supposed to to make it worth their while. This is illegal.  Also, many states have restrictions for what notaries can charge for travel fees.  Many notaries overlook these restrictions.
 
Journal thumbprints and notes
It is critical that notaries get the right thumbprint of the signer in their journal, especially for deeds and powers of attorneys.  This is a great way to deter fraud, and will keep a notary out of court in many instances.  Additional notes are important to keep in a journal too.  If a notary goes to court, they will never remember a signing that took place years ago, unless some notes are kept about anything unusual at the venue of the signing, or anything that is unusual about the signer.
 
Also see:
Everything you need to know about thumbprinting
http://www.123notary.com/forum/topic.asp?TOPIC_ID=4019
 
Backdating
Almost all signing agents will be asked to backdate at one or more times during their career.  Don’t do it.  Backdating is illegal.  Backdating means putting a date prior to the actual date of the notarization on a notary certificate. The date of the notarization is when the signer signs the journal, although the signer can sign a document before the notarization of an acknowledged signature.  Here is some more information about backdating.
 
You might also like:

What do you do if asked to backdate?
http://www.123notary.com/forum/topic.asp?TOPIC_ID=4029
 
What is backdating?
http://www.123notary.com/forum/topic.asp?TOPIC_ID=3920

Signing agent best practices: 63 points
http://blog.123notary.com/?p=4315

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http://blog.123notary.com/?p=19459