I saw this article on things on to say to mothers.  Worth reading!

8 Things Never to Say To moms 

Several things I wouldn’t say to anybody, not just moms.

A good rule of thumb is to be kind in your intractions.  Telling someone they really need to dye their hair (if it is not your very best friend in the world) isn’t helpful.  The other day one of my bosses said that to me.  Instead of being helpful (which I know her and she was genuinely trying to be helpful), I wasted moments of my life worrying about my hair.  Just saying.
So..  Ask yourself if what you are saying is helpful or hurtful (before you say it.)  Be Kind. Be Kind. Be Kind.