On YouTube, I loved Socratica. Their videos are short and well edited; they appear futuristic and serious, but that's what makes their tongue-in-cheek, dry humor so funny. Lastly, I have learned a lot in my career, not just about Python, but about ArcGIS and other languages by making mistakes and learning from those. Python is one of those languages where you can try stuff, right in a Python command line, and see if it works or doesn't. Training will help you develop well-organized, well-written, and well-documented Python. Always remember to document not just what your Python code is doing but also why. What problem does it solve, who asked for it, when did you write it, and any warnings to offer people who find your code later.
