There are two applicable rules here: names or terms of direct address are set off with commas (as in "You know, Dana, that's a good question."). Interjections like "hey" are also typically set off with commas. The first would require a comma before "honey" or "hon", and the second would require one after "hey". If you left out "honey", you'd still write "Hey, how are you?" If you left out "hey" (and moved "honey" somewhere else so that you could have a comma before it), you'd have "How are you, honey?" Either way, you end up with a comma after "hey" and before "honey".