The one thing you should be careful of is “backhanded insults” .
For example, don’t say to someone,”Wow, you look so nice today” in a way that implies that they don’t usually look nice and that you are surprised.
Once, someone who hadn’t seen me in a while said, “You look so good. You didn’t used to look so good!”
Being that the person was who they were I wasn’t particularly insulted. 🙂 I just thought it was funny.