How did you learn machine learning?

I'd start with An Introduction to Statistical Learning - a strong background in statistics is key, especially for being able to work with models and understand their limits and how to adapt them to your own use case. The pdf for the book is free and available here: https://www.statlearning.com/

For real, this is an amazing book and it's such a gift that they have it free online and with a python version - I learned with the first edition having to translate the R code to python! I wouldn't start with The Elements to Statistical Learning - that has a much heavier emphasis on the math and theory and is hard to get through!

i learnt most of it many years ago when it was called statistics and optimization.