Long-timers of this lifestyle, what was your rookie mistakes from the earlier days?

For me, my early mistake was two-pronged. First, I acquired unecessary gear & equipment. Second, I spent a lot of money on some of the best gear & equipment. I did a ton of research and preparing. In hindsight, not only did I over-prepared, I spent way too much money when the cheaper alternative worked just as well (often even better).

Case in point, while my Jackery 1000 Plus has become a good investment, I admit that compared to less popular brands, it's more expensive, and offered less capacity. Ergo, it's bought it for the name brand and the hype.