Well it's been a long ongoing journey. I had the good fortune to meet some good builders shortly after I got the bug. They weren't necessarily totally historically correct, but they knew good looking architecture, and were good craftsmen, and willing to share their knowledge with a beginner who wouldn't stop asking questions.
Being able to see things done well first hand, is pretty hard to beat.
The second big thing was being there at the start of Gunmakers Hall at Friendship. There I eavesdropped on conversations of the very best builders at the time, and saw some of the finest contemporary work of it's day. I hung around there so much that I eventually joined in the conversations, and got an immense amount of great advise from those builders.
The last big item on the list was attending a couple classes at WKU.
Along the way I've built a modest number of guns, and taken every opportunity to inspect whatever original work that has presented itself.
Finally, I try to be my own hardest critic. I usually know what can be improved.
Jeff