I learned how to ride backwards before idling. To Idle or super idle you have to change direction and that is much harder than the riding backwards. Wear a helmet, elbow pads, gloves and a knapsac with a sweater inside if you feel that you have to. Falling while learning to ride backwards is not that danderous as long as you are riding on a flat area. Skate rings, basketball and tennis courts, Gymnasiums are all good. Do not try to learn how to ride backwards on a road with sidewalk curbs or other things that can hurt if you fall on them. Mount and hold onto something. Concentrate and just push off. The hardest thing is getting your strong foot to come up after the 6 O’clock position. Pedaling backwards is just not natural. After a while you will get it and start improving real fast. Just think of how long it took you to learn how to ride! It still took ma a couple of months after learning how to Ride backwards to be able to change directions with a hight success rate. Learning to ride backwards really improved my MUni riding. My UPD rate dropped big time as I mastered riding backwards. The next big revolution came when I learned to pedal with one foot.
I fell backwards once: flat on my back whilst riding forwards. I think I hit a wet spot on the gym floor for all I was doing was a slow, gentle, even paced, straight line, forward. Nothing broken. However it hurt like hell, enough to keep me from unicycling for a month, and I don’t want to repeat the experience.
So I am now learning to ride backwards, and taking great care not to fall off. It means not, so far, letting go from the wallbars for more than a second or so. But it IS enabling progress at an unambitious but pleasing rate. Some of the tips in here will also undoubtedly be helpful.