I began canoeing by myself all summer long at my family's lake cottage in Maine from age 8 to 16. Taught myself. But in retrospect, not much.
I began with the goonie stroke, as everyone naturally does. I "invented" sculling and draws and some other things. I learned I could control the canoe better from near the center. When someone told me that the J stroke was better than the goonie stroke, I began using that, painfully and uncomfortably, until I finally learned how actually to execute a J-ish correction when I was 40 (below).
So it went, on and off with rental canoes from time to time, until I was living in northern California in from 1979-1982. In 1980, I took a formal class in whitewater kayaking from experts at Western Mountaineering, such as Jeff Jones and Reg Lake, which started with pool rolling sessions and ended up with training on the American River, learning about eddy turns, peel outs and ferrying. After dumping five times in class 3 Old Scary rapid and only successfully rolling once, I decided I really liked technical whitewater paddling but didn't like skinny, constricting and claustrophobic (to me) kayaks.
So, I decided I would pursue whitewater paddling in my newly acquired Mad River Explorer. I somehow talked my way onto Sierra Club whitewater trips and paddled all sorts of rivers in the Sierra Nevadas and California coastal ranges. There was lots of informal instruction from open canoe experts there such as Bob Foote.
When I moved to Woodstock, NY, in 1982, I hooked up with the Appalachian Mountain Club, the NY/NJ chapter of which was heavily influenced by slalom racing and the Millbrook canoes of national racing champion John Berry (ME, Flashback, MJM). I took formal whitewater lessons from John Berry and Keech LeClair on the Hudson and Schroon Rivers.
I began open canoe slalom racing, which is the best way to quickly hone technical whitewater skills and suffer immediate penalty for technical skill mistakes. I began paddling with the Connecticut AMC, eventually becoming a member of the Whitewater Committee, a regular trip leader on the class 3 and 4 trips, and the co-creator and co-instructor of the solo whitewater curriculum.
So, by 1984, I was pretty much a competent class 4 whitewater canoeist, but when I went to paddle with Mike Galt and Bardy Jones in Florida that winter, I found out that my flatwater J stroke was inefficient and that I was incompetent with many of Galt's highly technical flatwater maneuvers, later codified by the Freestyle community. I bought a Bardy Jones Express (BJX) canoe from Galt, and my J correction finally clicked when I was lost and paddling alone in the Okefenokee Swamp on my way back to New York. Actually, what clicked was some combination of what I would now call the C stroke and Canadian stroke.
So, it took me 32 years, from age 8 to 40, to learn how to do an efficient flatwater correction stroke. I probably could have learned it in 20 hours of formal instruction and practice. I have since observed that many competent whitewater canoeists do not know technical flatwater technique, and that most flatwater-only technical paddlers are lost in swift currents and real whitewater.
In the summer of 1984 I bought my first decked canoe, got rolling instruction from Clarke Outdoors, and practiced 300 rolls in the lake in Maine. In the summer of 1986, I did 300 rolls in my new Whitesell Piranha open canoe in the Maine lake. Always seeking to improve my skills.
I'll skip my eight years as a sea kayaker and five years as a Hawaiian outrigger canoe paddler in my 50's and early 60's, all of which involved a lot of training and learning, and pick up in 2009 when I decided to go back solely to open canoes.
I still couldn't paddle with the flatwater finesse of Mike Galt that I had seen 25 years earlier, so I decided I would take instruction in Freestyle canoeing, which had long since evolved a teaching curriculum, its own nomenclature, and a set of optimal canoes. So, I took instructionals in the Adirondacks and Florida, which taught me some new maneuvers and honed others I was already using. The instruction was excellent.
During all the 40 years or so since 1980, I bought many paddling instructional books, later videotapes, later DVD's, and later internet videos, all of which are helpful but no substitute for actual on-water practice or formal instruction.
Summarizing a long life of self-instruction and professional instruction, I would highly recommend to anyone who wants to become a competent technical canoeist in all waters to take professional personal instruction in flatwater freestyle canoeing, river canoeing, and whitewater canoeing. That will only take up about 72 hours of your life, but bring a lifetime of improved paddling enjoyment and confidence.