Down-Air, l-cancel, shine.
RINSE AND REPEAT.
Maybe throw in some up-tilts or back airs if you're feeling exceptionally SAUCY.
Disclaimer: I am an absolute Falco noob & this is my personal experience with this combo. Don't interpret my writings as authoritative.
This works on floatier characters quite well but requires a little bit of nuance to pull off.
1st: You have to match the height they fly upward with both of your jumps. Try to be a little bit above them.
2nd: You must dair & fast fall with a timing that has you hit the ground first & leaves them in hitstun long enough to get shined again.
3rd: You must hit the ground where they're going to land so you can immediately shine them. Otherwise prepare for a tech chase.
4th: Waveshines help your positioning on a shine followup
5th: This combo is very %age dependent.
More advice from one noob to another:
If you cannot finish the combo, use the time to position yourself rather than go for a followup. This practice will REALLY help you out. If you shine someone while you're both underneath a platform, waveland to the above platform & go for another shine. It takes practice but is totally worth it. Execution should be the least of your worries, so practice it until it becomes subconscious.