Good question. For me personally, my best method for short hopping at first was using solely the tip of my thumb and basically lightly running it down off the button. This way, the button didn't register a full press (aka a full hop).
On the gamecube controller, I used to do this on the Y button. I developed this awful habit of running from Y to A in a consecutive motion and using my angled aerials without even touching the c-stick. Needless to say, this limited my aerial game pretty hard, so I converted to running my thumb sideways off X and immediately going to the c-stick or tapping A for a nair. I've also tried to get better with simply tapping instead of sliding off, it's just muscle memory in all honesty.