That's an impressive set of questions. Either this thread will get very long, or people will select just one or two to answer.

In my case, I struggled not at all with starting backpacking. I'd car camped and day hiked since early childhood. In my middle teens I made the jump to backpacking and my parents were happy to consent to my plans. It was a natural development.

Because I began at a young age, I was adventurous and adaptable, so my early mistakes never daunted me. I lost food to camp-robbing critters, got badly sunburned, got the runs, got lost and then figured out how to get located on the map again, got my sleeping bag wet when the tent leaked, and so on. Having done all these, I now don't have to do them again, because each time I learned something and applied it to future trips.

In the off season I was eager to learn new things by reading about the experiences of others, especially books, or else news stories about searches and rescues, or about searches and recoveries.

Mainly, learned about the value of planning, planning, planning. Making lists. Collecting maps. Consulting trail guides. Collecting valuable new tidbits of information about a better way to do something, store something, carry something. It has been more than 40 years now and I am still studying up, collecting valuable hints, sharpening my skills.

What makes me nervous? Turning this on its head, they are the same things I am most vigilant about:

- sudden turns in the weather, especially getting caught up high and exposed in a thunderstorm.
- fording streams with a strong current
- crossing talus
- complacency about risks, especially about my casually or impatiently accepting a series of small risks until I suddenly discover I've dug myself into a deep and dangerous hole
- falls or injuries
- hypothermia
- dehydration

EDIT: Reading over that list, I guess that, even though I was never a boy scout, I wholeheartedly agree with their motto: Always Be Prepared. It is great advice for backpackers.