It has for some time been a cause of distress to me to see otherwise courteous people signing titles to their names. From my earliest years, I had been carefully instructed that this was a "no-no." And as a beginning teacher, it was an easy way to detect forged notes allegedly from parents.
Rule 1 Never sign a title! Write Mary Jones not Mrs Jones, Father Smith, Dr Watson, Sr Mary Veronica, General Washington, Queen Elizabeth, etc.

This reflection is being written today because my own high school, where I was taught never to use Mrs before a feminine first name, has published a web page with a faculty list violating this very rule! Mrs should be able to be read "the wife of" and should be used before a masculine first name or a surname. Use Miss or Ms before a feminine first name.
Rule 2 Never use Mrs before a feminine first name! Write Mrs John Jones not Mrs Mary Jones, etc.

NOTE 1: The title Ms was invented to avoid this problem and the need to know if the person is married or not! Use Ms Mary Jones for Mrs Jones if you must.

NOTE 2: The faculty lists at more etiquette-aware schools look like this:

Mr Anthony Able
Dr Boris Book
Mary Jones (Mrs John)
Miss Jane Roe
....