Update:
I don’t mean to brag, but yesterday evening I had my biggest eureka moment ever with unicycling when I finally figured out how to transition into idling from riding. After dozens of failed attempts, I finally figured out how to do it and did several cycles before a UPD, and a little later did 26 cycles. This means no more wall! This is an even bigger deal than when I figured out how to free-mount.
Today I did even better: 40 idling cycles while riding, and 10 to 20 a bunch of times. I can transition into idling most of the time now, though sometimes screw up and end up doing 2 or 3 before a UPD, particularly when the ground is uneven. I can sometimes go back to riding after idling for several cycles. Transitioning back to riding isn’t all that difficult. I can only idle with my right foot down though, not my left foot. As soon as I master my right foot, I will work on my left. It seems the general idea is that once you learn with one foot, you’ll learn with the other much faster. I hope this is true of me. To those who have taught others or are very experienced in these matters, is this true?
I found John Foss’s advice helpful(and advice throughout this forum and Youtube videos, thanks everyone!), but also started to find that transitioning slowly, gently, and gracefully into idling is the way to do it. When I kept failing at it, I was stopping too abruptly, and I was nervous. Very very little pressure on the pedals is the way to do it, at least this is how it worked for me. Then of course start applying pressure to the dominant foot to initiate the idle, however, keep most of your weight on the seat.
Maybe after a few weeks of regular practice I will be a competent idler. Now I just need to learn how to hop onto curbs, go backwards, and 1 or 2 other free-mounts. Though I’m still a novice, and my idling is sloppy, my advice to those struggling with idling is to not give up! I don’t consider myself to be a fast learner, so if I can do it, you can do it. Practice a lot, but take breaks occasionally and breath deeply. Approach it like a meditation and make sure you have a lot of space, since learning to pivot is important for staying on the unicycle. Start from a wall, fence, or car, but give up your support as soon as possible.
P.S - Yesterday I ate a ton of mixed berries(blueberries, raspberries, blackberries) before my major breakthrough. I notice on this forum, and on some juggling and acrobatic sites, the topic of berries comes up sometimes because of some mostly preliminary scientific evidence that they may be good for the brain. My experience of course doesn’t prove anything, but I wonder if they helped me in some way. Even if they didn’t, you can’t go wrong eating more berries.