Since you are guaranteed to make mistakes out there, why not learn vicariously from other thru-hikers in order to limit your learning curve.
10 Mistakes I Made While Thru-Hiking - FarOut
Avoid These Common Beginner Hiking Mistakes
Thru-Hiking Appalachian Trail Conservancy
10 Mistakes I Made While Thru-Hiking - FarOut
Hiking The Appalachian Trail: 15 Tips for a First-Timer
How to Thru-Hike the Enchantments — The Grah Life
Going Hiking? Don't Forget These Safety Tips. - The New York Times
10 Favorite Sections of The Appalachian Trail
Mistakes I Made On My Appalachian Trail Thru-Hike – Wildwood Hiking Co.
7 Mistakes That Could Ruin Your Thru-Hike! (Appalachian, Pacific Crest, Continental Divide Trail)