If you would like to continue to enhance your R prowess, here is a suggested subject tree:

  1. Master the Advanced R Hadley book
  2. Functions - get comfortable writing your own functions for repeatable tasks.
  3. Github - any coder should use some kind of source control, R’s integration with Github makes it a natural fit.
  4. Create a package - it doesn’t have to appear in CRAN (yet!) but its a small step from sourcing a file of your custom functions to loading your own private library.
  5. Shiny - being able to quickly create interactive webapps when asked for a report is always impressive
  6. Kaggle - practice your machine learning with public datasets in a friendly competitive environment
  7. Advanced packages - get a package on CRAN, or contribute to the development of one on Github. Start using tests, Travis and coverage
  8. Start using unit tests via library(testthat) to ensure robust code.