So, what more advice could I give the aspiring ukemi artist?
Do a lot of it (I mean a LOT)
I know I've said it before, but the main obstacle standing in the way of great ukemi is good ol' fashioned fear. Our Subconscious Mind is afraid of hitting the ground because it thinks it will get hurt. The only way to change it's opinion on the matter is to convince it—through bazillions of repetitions—that it's okay to fall.
I've also gone into the benefits of a crash pad, but as far as I'm concerned, I can't emphasize it enough. As a brown belt, I would spend the ukemi time during class alone with a crash pad. I would start on one side, roll, get up, and roll back the other way, over and over, until it was time for the class to move on. By then, my legs were so rubbery, I could barely stand. 15 years later, I still use the crash pad.
Get the basic, fundamental rolling breakfall thoroughly ingrained. All the other versions—the flippy air falls, guruma falls, sumi otoshi falls, sideways rolls, backwards flip in mid-air osoto gari falls, etc.—all come from having the basic version firmly implanted, period.
Then, have someone hold your hand while you do your big, flippy air falls on the crash pad, over and over. Do it until you're sick of it, then do it some more.
Hey, you asked, and I'm telling you. Okay, well maybe you specifically didn't ask, but to those who do, this is what I recommend. Many would call this approach to training as "misogi" or purification. And unfortunately, most people are unwilling to go there.
Humans get bored fairly easily, it turns out. Often times, I assign students a given technique or drill and pair everyone up to practice. Guess how long it lasts? Most will do it three, four times and then look around and wonder if I'm going to give them something new to do. Why are you stopping, I wonder. Mastered it already, have you?
I remember, years ago, Chuck Caldwell Sensei having us do uchi komi drills in judo from time to time. We'd take osoto gari, for example, and one of us would load it up 19 times in a row, and then throw on the 20th. Then it was the other guys turn. Then we both did it again. Maybe even a third time. Talk about your body turning to jelly. Not a day of judo goes by that I don't thank him in my mind, and I guarantee you, my osoto is all the better for it.
Something within us wants to be constantly entertained, and expect the instructor to keep things moving, cramming as much info in as possible. But there is something to be gained from isolating a thing and drilling it until your eyes go blurry. No, scratch that. There's mountains to be gained.
This applies, of course, to more than just ukemi, but that's the topic, so go do your rolls. When you start to get bored, keep doing them. When your legs start to ache, keep doing your rolls. When you just want to stop, keep doing them. Push through it, and keep doing it until your mind goes white, blank and numb, unable to focus on anything.
The roll will engulf you, swallow you whole. Let it.
Then you'll be ready for step 4...
Amazing ukemi, Step 1