Hastie and Tibshirani teach a free course based on this book on Stanford's OpenEdX (https://online.stanford.edu/courses/sohs-ystatslearning-stat...). I highly recommend taking this course or reading the book before delving into ESL. IMO, ESL is excellent as a reference, but trying to learn by reading it linearly is not an optimal time investment.
Now if only a similar course existed for Wasserman's "All of Statistics..."