As a half-back in rugby league, the key in my opinion is the players around you. If you can drag one of the bigger forwards into a position around you before throwing a dummy to them, the defence will naturally look consider the bigger ball carrier as the main target. You just need to be confident enough to start bossing people around if it helps the team. Other than that, footwork is the key as well. If you can target a gap between two sliding defenders then there is a great chance that you will catch one of them being a bit lazy and not sliding across. Either way, you have given them a decision to make. It's pointless just throwing a dummy if you haven't created anything to cause the defensive line to make a decision.
