James Gray is a very clear writer, I think, who has generously left some short ebooks online. He is a naturalist and moral realist, and this link takes you to one of the best surveys of the nature and history of meta-ethics I have ever read.  This is an area that textbooks cover very poorly – tending to over-simplify or mislead the student, which produces a nervousness or confusion when handling essays on this topic.  But if you can clarify things in your own mind, it is possible to score very highly. PB

http://ethicalrealism.files.wordpress.com/2009/12/contemporary_metaethics_part_1.pdf