The best way to learn how to wrangle data is practice, especially outside of academic settings, where the example data is not necessarily reflective of real-world data.

Helping others wrangle data is one of the reasons I publish my Jupyter notebooks open-sourced. A few examples my data wrangling with R:

Processing Stack Overflow Developer data: https://github.com/minimaxir/stack-overflow-survey/blob/mast...

Identifying related Reddit Subreddits: https://github.com/minimaxir/subreddit-related/blob/master/f...

Determining correlation between genders of lead actors of movies on box office revenue: https://github.com/minimaxir/movie-gender/blob/master/movie_...