Be kind and be respectful. Especially when the person who will feel the brunt of your actions isn’t in the room with you. If you’re unsure, imagine being stuck in an elevator with them. What sort of a conversation are you having?
The spoken word disappears as soon as it is uttered. The written word is immortal though. Time is a great editor. So consider using it before printing/posting/sending.
If you play a Christmas song in any month of the year bar December it will ruin the mood at a gig. That doesn’t mean they are bad songs – you just played it at the wrong time. Consider that the next time you are thinking of ditching one of your songs.