Printreading based on th 2008 NEC would be a good start. The best way to prepare is to do the tests in the book, however that gets to be alot of work. Depends how prepared you already are. It really helped me and alot of questions on the test were word for word from the book. At least that 's how it was back on the 2005 NEC. It also helps to have the answer sheet for the book.
Also, practice your calculations (services, motor feeder, GEC's ect...) and there might still be a test on the North Dakota Wiring Standards. The standards are available on the NDSEB web site.