For me, I have gotten to the point where I give a warning to my ADC that I WILL highly likely end up killing botlaners with my kit...
Endlessly harassing is often a good technique I find as it either 1: leads the enemy support to build MR instead of armor, or 2: the support building armor still gets hit hard and being forced out of the fight... This forces the enemy ADC to either play extremely defensively and lose farm to tower, or play very aggressively and take big risks. of course, this depends on the ADCs and the enemy support, but unless the enemy support can reliably heal, a poke v poke lane will either go very much in Sona's favor, or be a stalemate.
When I myself play carries, I honestly don't care who gets a kill as long as the enemy dies...