My strategy for teaching IELTS is:
1) ENGLISH SKILLS: If there's enough time, work to improve the student's English level through English training.
2) TEST PREP: Help the student gain an understanding of how the IELTS test functions. There are various books that deal specifically with the IELTS, how the speaking part works, the two tasks of the writing part, etc. (I always teach my students how to do a 5-paragraph essay for the 250-word Task 2.)
I think of it as two courses and think it's best taught as two courses. The first one is actually teaching English and the second one is teaching how the functions of how the IELTS test works.
ENGLISH SKILLS TRAINING
I have found that Interchange by Cambridge Universtity Press hits on almost all of the types of content that IELTS does such as the environment, education, work, news, movies, food, people, etc. In addition, it is teaching skills for reading, writing, listening, speaking. There are some examples below from New Interchange level 3.
IELTS TEST PREP SKILLS
The second course can be a short and it's rather easy for the students to get the point of how different parts of the test work. Once they have this test-prep course they should understand it. I believe this one bit of training can help a candidate improve their score by one band level. I suppose some people would question that assertion so let's look at it another way. This training can help a candidate avoid making mistakes that could cost him one band level.
Now if they should fail to get the score they want in IELTS they do not have to take this second course, the test-prep course, again. Not scoring high enough, means that their English level is not high enough and they need to work on their English skills which is a much bigger job.
For this effort I have used various test-prep books for IELTS. All of the ones I have tried have been useful but I guess I wasn't relying on them so completely, using them more as a framework to work from, as I have a lot of things about the test that I have learned and use that as a resource when teaching IELTS. So I have no strong recommendations to make on IELTS test-prep books but am interested to hear other's recommendations on those as well.
SOME TOPICS INTERCHANGE COVERS:
Personality types and qualities; relationships; "turn ons and turn offs". Describing personalities; expressing likes and dislikes; expressing agreement and disagreement; complaining Relative descriptions of people; making inferences. Writing about a best friend. "Friends Again – Forever!": Reading a narrative about friendship. "Personality types": Interviewing a classmate to find out about personality.
TALKING ABOUT WORK, JOBS, EMPLOYMENT, CAREERS
Unusual and exceptional jobs; job skills; summer jobs. Giving opinions about jobs; describing and comparing jobs Gerund phrases as subjects and objects; comparisons with -er / Writing about career advantages and disadvantages. "Strategies for Keeping Your Job": Reading advice about behavior in the workplace. "The best and the worst": Finding out about classmates' summer or part-time jobs.
DISCUSSING NEWS AND CURRENT EVENTS
The media; news stories; exceptional events. Describing past events; narrating a story. Listening to news broadcasts; listening to a narrative about a past event; making up stories. Writing a newspaper story. "Strange but True": Reading tabloid news stories. "A double ending": Completing a story with two different endings.
DESCRIBING COUNTRIES AND CULTURES
Cultural comparisons and culture shock; customs; tourism and travel abroad. Expressing emotions; describing expectations; talking about customs; giving advice Noun phrases containing relative living listening to descriptions of and opinions about customs. Writing advice for a visitor to your country. "Culture Check" Reading and completing a questionnaire. "Culture clash": Comparing customs in different countries.
DISCUSSING THE ENVIRONMENT AND GLOBAL PROBLEMS
The environment and world issues. Identifying and describing problems; offering solutions. Listening to people talk about problems, solutions, and accomplishments. Writing about local issues and offering solutions. "The Threat to Kiribati: Reading about an island that is sinking into the sea. "Community planner": Solving some small-scale environmental problems.
TALKING ABOUT THE PAST AND HISTORY
Historic events and people; biography; the future. Talking about historical events; giving opinions about the future. Listening to historical facts; listening for opinions about public figures; listening to predictions. Writing a biography.
"The Global Village": Reading about political and technological changes. "History buff": Taking a history quiz.
DISCUSSING PERSONAL LESSONS AND EVENTS
Milestones and turning points; behavior; regrets. Describing yourself in the past; describing regrets about the past; describing hypothetical situations. Listening to descriptions of important events; listening to regrets and explanations. "If You Could Do It All Again": Reading about three people's life choices. "If only . . . .": Imagining different possibilities for yourself.