Never really thought about what would be the canon kill method for each target. I think that the closest thing to canon kills are the ones we saw in the trailer/ cut scenes.
Hayamoto Jr.: Dressing as Sushi chef and serving poisoned Susih
Fritz Fuchs: Drowned in the pool
Fernando Delgado: Fiber Wire
Dom Osmond: Bullet into the head through the mirror
Viktor Novikov: Light rig
Silvio Caruso: Poisoned wine
Claus Hugo Strandberg: Briefcase bomb
Personally I believe 47 would kill most of his targets by poisoning their food/drinks, with the sniper or explosives instead of relying of complicated plans. It also means that he’s either far away when the target dies or at least isn’t immediately suspicious because he’s standing next to a dead body with a fiber wire in his hands.