I must admit... I am a Noob. However, Whenever I do play PVP I generally start off with a good luck message and end on the traditional GG (Good Game).
People should realise that others playing are doing so for the enjoyment of the game and the pleasure of good old competitiveness, if they abuse people continuously then they will (in a very short time) have no opponents to play against, spoiling the game for not only others but also themselves.
This game is such a great way to pass time whilst enjoying the gaming competitiveness and meeting new people that have the potential to help you out in the future.