Per the comments on the article I'd also advise "<-" for assignment rather than "=", reasons (in no particular order):

1) Google says so: http://google-styleguide.googlecode.com/svn/trunk/Rguide.xml

2) It's the accepted convention of the language. When she looks things up of SO, they'll use it; if she looks at a package's source, they'll use it.

3) In RStudio it's "option+hypen" (Mac) to type the four-character " <- ", so no extra typing required.

4) Statistically-speaking, things like x = x + 1 makes no sense

5) You need "<<-" for the occasional global

6) 2 -> x