Over the summer, I've been taking an incredibly informative course online called Sabermetrics 101. Put together by a Boston University professor, I'd recommend it to anyone looking to get an in depth peek at the world or Sabermetrics. Even if you don't want to commit that kind of time, the course is organized into different tracks, or aspects of Sabermetric knowledge, so you can pick and choose what you want to learn. For me, the most valuable parts of the course were the comp sci lessons, which focus on making database queries in mySQl, and doing data analysis/creating graphics in R Studio. What follows is ostensibly informative and hopefully interesting, but is really just me working through the R language.