I'm still practicing, but I think it looks totally sweet to jump off the edge, align yourself horizontally, FW into the opponent, slightly to the farther side of them, so they get knocked off the edge when they try to edgeguard, then fall after them and d-air sweetspot.
Like many people will tell you, you have to catch them unexpected. If you practice your 16-directions, you can do this from the air, so they don't really see it coming, they'll probably think you're going for the ledge. Don't do this too often, though. The key to a fantastic player is unpredictability, imo.
Alternatively, you can just distance yourself, and just FW into them (maybe a few mindgames before hand to confuse them) from the stage.
Another method, is to just lure them to the edge, dodge, Dsmash and go after them in the same kinda way.
Basically, if you can arrange it so that they have to come up to the stage, it is easier to dair them, since they're coming into your foot. Just make sure you don't underestimate their recoveries.