well theres nair/dair on the back on shield that works on some people, you can also shield poke certain characters with nair, etc etc
but what I find works best for me is using a lot of feinting to draw out a response and punishing from there, much better then just straight up approaching with an attack.
anothing thing very similar is using 'walk spacing' sorta walk up to them to get them to throw out an attack, but then you walk back and then ftilt them, sounds kinda simple and easy, but it can be hard to apply, but when you do it right its really quite annoying for your opponent as it messes up their spacing and ftilt can be a relativly space move.