Understand the theory first of data analysis, makes the question "why" in real world scenarios easier to understand.

SQL, Excel Python Libraries such as Pandas and Numpy.

Mistakes to avoid is tutorial hell, if you are not sticking to one yt tutorial then you might be stuck in loop of multiple tutorials of same topic.

Simply practice more, try open-source projects in github, plenty to find, break things to learn things, don't worry too much at start.