Honestly I'd focus on using it a couple times and the syntax should feel very natural afterwards. Understanding what the `aes` command is doing is the most important: it's mapping a set of features to the plot, and then you are adding various `geom` objects that visualize those features.

There is a book: http://ggplot2.org/book/ if you want to get more into the nitty gritty.

I have found this to be an excellent tutorial: http://tutorials.iq.harvard.edu/R/Rgraphics/Rgraphics.html

It explains the use but also the philosophy and design pretty well.