3-4 man gank tips?

Hello everyone, so I see qtpie and gosu and tyler1 push the lane with no fear hence there godlike mechanics. 2 or 3 people always come for them and whether or not they take a 1 for 1 plus tower it's worth. So on to my qustion, assuming i'm an adc(ranged) what would the best bet be for kiting the 3 champs. And who would I focus? Would I just focus whoever is closest to me and kite him, or focus the guy with the cc, or focus the guy with the damage?

Thanks for reading my post looking forward to your guys responses