Granted, I've talked about some of this before, but I've also thought about it even more since then. Hopefully, there's some new information here for all those dedicated readers out there.
Whether or not you've followed my supremely valuable advice in step 1 and started while you were young and fearless, you can still develop super human falling skills by moving on to...
Take your time, and start low
Okay, that's actually two pieces of advice, but in a way the two go hand in hand. One of the drawbacks of starting young is getting in too big of a hurry to get to the big, hairy falls. It's great that they're willing (or perhaps dumb enough) to do them, but you need to build a solid foundation of basics first.
Most folks I've talked to over 30, however, are more than willing to take their time, which is good. That evolutionary tendency to resist falling takes nothing short of time and repetition to overcome. There's no shortcut, folks, sorry. So you might as well sit back and enjoy the process.
Because rushing on to something you're not really ready for will most likely get you hurt. And even if it's not drastic—maybe you just bump your shoulder and make it sore for a couple of days or weeks—you're Subconscious Mind will positively freak out. I told you falling was stupid! it will scream at you. From then on, your Subconscious Mind will make little tweaks and adjustments to your falls to try and protect the injured site, which will actually make your overall fall worse. And trust me, it will take months to get over that and fix it.
And since the hardest part of falling is convincing ourselves that it's actually safe (when done right), start as low to the ground as possible. Doing so will first, isolate certain key elements of falling like tucking the chin, breathing out when you slap, etc, and second, if you're not traveling very far to reach the ground, the impact and chance of injury will dramatically decrease. Take for example a few of the drills here:
Now, after you've done that for a while and it's feeling comfortable, you can start to move your way up to standing. Once there, it's time for step 3...
Amazing ukemi, Step 1