Great example of what not to-do, from The Post Money Value blog (by Rick Segal) :
I’m in the Barnes and Noble Bookstore in Burbank.
This is a conversation I just had with management:
Them: “Hi, may I help you?”
Me: “I was wondering why you have a sign in the window that says “Have you checked out our selection of books in Spanish?”
Them: “Well, sir, we have many Spanish speaking customers and we want them to know about our selection.”
Me: “Oh. How come the sign is in English?”