I’m getting to where I can idle about a minute
With my right foot down (lower). There is only 2 ways to idle, I learned left foot down first, on a 19 ". I bet a skinny tired 20 " is easier or the same. Then it gets harder as the wheels get bigger. The 24 isn’t so bad, but I have never gone reverse on the 36. Maybe I should buy a 29 LOL
I learned to idle watching movies. Wasn’t scary at all, but then I hate horror or gore, so I was laughing or crying instead.
Consider learning on a small wheel while watching movies. Have a hand hold nearby, so you don’t have to remount every time you lose balance. Just go for it. Try to keep your balance, while making up bs with the lower foot on the pedal. Make it up as you go along. Can be a bit dull and slow. So watching movies is the hot set up IMHO. It has taken many more hours to get the basic idling feel, then it did to learn basic straight riding, for me. I think I started to idle a few months ago, watch a movie a day, and I get tired or lose my balance after a minute or so. So it is much harder then riding forward, many times harder for me, don’t give up. It just gets better slowly.
I can ride 100 feet reverse before I start to get scared. I need to get better at doing the 180 look back. I think I might wear a helmet before I try this on the 36. It really is all just instinct to tighten up at a certain point. I am pretty sure as my balance improves and I get better at the snap back glance, riding backwards will seem normal.
Anyway, riding backwards, and idling are related skills. If you can idle with either foot down, riding backwards will seem ok. It’s the same as changing your lower idle foot.
It is a weird tech though, more about time spent, then substance or comprehension, I can’t think of a single good tip. Pirate movies !LOL, and put in your time on the seat, and it will work for you.