So, when you’re setting the position of text in ggplot, you may have to use the hjust and vjust commands. Depending on your demands, and if you don’t understand what they’re doing, they might seem hard to use. I found one script that produces the graph below, as well as an excellent discussion here: http://goo.gl/TaUsG

I have modified the code to produce the following handy “guide” to when to use which level for each of the various values in combination with three different angle settings. Again, this is someone else’s work, but a re-post might be helpful: