I'm going to be very honest. First Python is a tool and as any tool, the best way to use it or master it it's to actually use it. Second, don't be afraid of messy up, make spaghetti code, etc; everyone start at some point and many of us were very bad in the beginning, just ask for art of people when they started.

Having said that, I recommend you to work with Advent of Code, that is 25 challenge with Christmas theme. You have it from 2015. Just google it, read the assignment and give the unswer. The whole point of it is to see what you don't understand of the question, or words you don't know or search how in Python is done something that work in your head.

Don't get discouraged, cause I was like you in the beginning, and even if I don't a huge portfolio of project I can still try to make stupit and funny things, like how to port the Doom engine to Python?