So many lines of code that comes handy - thank you all for sharing!
As @jessemaegan I start with commented header with project name, date, purpose and other extra information both for me and anyone else who uses the script.
Sometimes when it's just a quick thing, I go with Sys.setlocale("LC_CTYPE", "en_US.UTF-8"), though.
I never use rm() before, I tidy up R environment after each session. Does someone here does that too?