The level req for a bronze wrist band is 150. You could plow through the single player if you wish but i consider playground games better for grinding the XP. The king game mode is best way. As of 09/10/2014 i am getting around 35,000 xp for just finishing regardless of position. Good luck fellow achievement hunters.
This isn't a guide in any way shape or form so i do not expect thumbs up at all just a little shout to anybody who wishes to know