I learned to ride them a couple years ago. Started on a 20" and moved onto a 29er. After relocating to a new town and environment, early this year, I haven't gotten back on it. I'm pretty busy with my new bicycle and wanting to push my bicycling farther.
1. Learning to ride is difficult, and there are different approaches that people find success with.
2. It's fun if you advance.
3. Feeling comfortable riding/turning is a gradual thing. I guess I went from my first attempt in my driveway to where I could ride out on the roads, climbing/decending hills, approx three months.
4. I fell forward and backward equal percentages.
5. Start with a 20". Look for tips on YouTube videos. Realize that not everyone offers the same approach. Unless you live in a dry climate, invest in several redundant pairs of gloves, so that each pair has time to dry before you wear them again. Perseverance can be very sweaty.