I have one thing that I think gets over-looked.
I taught my children to call adults Mr. or Mrs. (last name).
I found that children who used Mr. or Mrs. were better behaved than the children who called all adults by their first names.
I have made exceptions with my daughter who has speech problems, and I would let her call some people by their first names if it was easier.
My son, however, is required to call most people Mr. or Mrs.
We do have some exceptions. We have a single friend of my husbands that my kids adore, and they call him Uncle Bill because he is like an uncle to them. They also call their real aunts/uncles by their first names.
I was brought up with the Mr. or Mrs (last name)...heck I still did it into my 30s...although I dropped most of it in my mid-20s after I had been gone and on my own for several years.
With my daughter it is generally Mrs or Mr (last name), but with many of our friends it is Mr. or Miss (first name) as that is the way most people I know prefer it to be done. Most of my friends' kids call me Miss Gabz and that doesn't bother me in the least.
We do have several close friends that she calls "Aunt" or "Uncle" (first name)......... that was done at their request.