9 times out of 10 I will play on
If you blunder your queen, do you keep playing or resign?

Play on because there's still a chance of winning. You could still have a chance of forking or pinning your opponent's queen (if they aren't too good).

I resign if:
- I have no pieces but the king.
- I have just a few pawns that will never hope to promote and my king.
- There's no way you're going to be able to checkmate (insufficient material for you)
I don't resign if:
- I have a plan
- I still have some of my pieces left
- If I think I might be able to force a stalemate
- If my opponent has like 30 seconds left

https://www.chess.com/tournament/march-spring-iv/join
Could you join in my tournament?