How to learn Python effectively?

I am planning on learning Python by myself in order to learn more about computer science/machine learning etc. Because they are the fields that I want to learn in university and I just want to get to know them sooner. Some of the courses on YouTube are quite long and introduce many functions which I don't think I am going to use a lot. Do you guys recommend any free courses on Python that would fit my reasons for learning? Thanks a lot.

When I learn it, I practiced for at least 30 minutes a day after school. If there is a piece of code you want to try and make, copy the code from a source, and then re-write it. And re-write it again. And again. Repeating this made it easier for me because writing that type of code again and again embedded what I was typing into my memory. I also recommend trying to write code from what you have already learnt without copying anything. Quiz yourself not by assessment, but by writing larger scripts of maybe 70ish lines of code, minimum. Hope this helps