That's why they wrote Introduction to Statistical Learning[0] and also a video series for the same book[1]. Both books and the video classes are a must for anyone working with Machine Learning and/or Statistics.
[0] http://faculty.marshall.usc.edu/gareth-james/ISL/ [1] https://www.youtube.com/watch?v=5N9V07EIfIg&list=PLOg0ngHtcq...