Since you are guaranteed to make mistakes out there, why not learn vicariously from other thru-hikers in order to limit your learning curve.
Epic Trails: Seven Best Thru-Hikes of the World
Guided Hiking Trips in USA & Canada
Hiking's Triple Crown
Dangers of the Appalachian Trail and How to Avoid Them - Mountains with Megan
15 Common Beginner Mistakes in Backpacking and Hiking
Top 10 Mishaps to Avoid When Hiking the Appalachian Trail – AppalachianTrailClarity
7 Things I Absolutely Hated About Thru-Hiking the Appalachian Trail - The Trek
Most Common Mistakes Thru-hikers Make – One of Seven Project
9 common mistakes to avoid while hiking and camping - Lonely Planet
Hiking The Appalachian Trail: 15 Tips for a First-Timer
Most Common Mistakes Thru-hikers Make – One of Seven Project
7 Reasons Why Women Make Great Backpacking Leaders On the Trail — She Dreams Of Alpine
6 Backpacking Mistakes to Avoid from an Appalachian Trail Guide - The Trek
Avoid these 6 common beginner mistakes that (Appalachian Trail) thru-hikers make
Hiking Guide for Beginners: How to Pack, Choose Trails and Stay Safe - The New York Times