Software Carpentry community [1] has a few very good tutorial guides and workshops for those who are new to R. Their main aim is for teaching basic laboratory skills for research computing. Others who are already proficient in R can utilize and adopt these materials for their own training and workshops.
The first guide is for clinical settings, doing data analysis for inflammation in patients who have been given a new treatment for arthritis [2]. Another is a general introduction to R for non-programmers using gapminder data for reproducible scientific analysis [3][4].