Try using IAD pin. You can get in faster that way since it sends you flying towards the opponent. As for the follow up after the pin as you fall use j.s > ADC, j.k, j.s or j.s > ADC , j.k, j.p, j.k. It's situational depending on the height of the character you're dealing with and the height you're at when you're coming in on them. Just experiment in matches and find what works best for you. There is another way but you should probably play some human players to get the timing down right, because if you're doing it wrong you'll get thrown as you land.
If you land a counter hit on an airborne opponent with pin just land and you can use these as launchers:
2p, 5p
2H
5k, 5k
2S, 2h
Sometimes it's situational depending on what height you hit them at with the pin. You should also try baiting AAs and throwing the pin closer to the ground. Makes it easier to get in.