Falcon takes feeling and prediction proress, but you cant have that until shffling is 2nd nature to you. My way of learning it was breaking it down into the 4 actions, Jump, C-stick an attack, Fastfall, Lcancel, and REACT
the reaction is the important thing, what you do with those precious moments you saved with the fast fall L cancel.
Faster you are, the better your chances at a nair or more uairs etc, and dont be afraid to let the combo go if they DI, and scare em with some dashdance, and get the grab.
If you wanna practice shffl combos on your friends, all you have to do is hit with a raptor boost, and then go for a neutral air, and then combo as much as you want, good other combo starters are of course the stomp, and just random nairs, neutral air is very hard to master.
Just incase you didnt know (trying to be helpful) the neutral air can be fastfalled in different ways for diferent effects, like you can fast fall L cancel it after the first hit and get a grab, or you can let it hang slightly longer for both hits and try to combo or knee.
The knee is implied of course. I cant explain the knee I worship its mightyness
edit :
Remember when short hopping forwards with a neutral air and hitting your opponent, to DI backwards as to let the 2nd kick hit them without you flying past, thus setting up your Uair x how awesome you are to knee.