I also HIGHLY recommend (great self-study books):
Cambridge Vocabulary for IELTS with Answers and Audio CD
Cambridge Grammar for IELTS Student's Book with Answers and Audio CD
Planet IELTS Helper
planetielts.com
Cambridge Vocabulary for IELTS with Answers and Audio CD
Cambridge Grammar for IELTS Student's Book with Answers and Audio CD
Planet IELTS Helper
planetielts.com