Remember...

to smile.  Smiles are contagious.

We were walking through the mall and Niko slid his hand into mine and said, "That lady just gave me an angry look."  I looked back at her and saw her back walking away.  "She may have been upset about something, and your eyes may have just been in her path of thought.  Next time, smile.  She probably wants to smile but needs inspiration.  Smiles are contagious.  She, or whomever it is, will have a hard time resisting smiling in return.  "