Academic IELTs necessitate some "skills" to pass with no difficulty if you wish to sit it with an unexpectedly high mark. Skills is not all equal to your real English proficiency, in this case you had better consult a qualified English teacher to enhance your skills of the test. 

I agree with Braeden R. but I would also like to recommend a different approach. I read a book years ago about juggling and it was really interesting because essentially it was about learning to juggle. In juggling you begin with one ball, throw it and allow it to fall into the other hand. repeat that over and over from one hand to the other. Important that should the ball miss your hand then do not reach but allow it to fall. Pick it up and start again. One ball juggling is then replaced with 2 ball juggling but the process is the same. Then when you are comfortable with 2 ball juggling then add the 3rd ball and continue the same process. Learning juggling is the same process with learning anything. Mistakes are so important to be seen in the right context. They are not to be hidden like a dirty secret, but assessed in a sensible way, how could I improve, what if I tried something else?

Attending English class relevant to IELTs in your country may be more practical to increase the possibility of passing the test. English proficiency can hardly be improved in a short time but the skill in sitting the test can be well improved through proper teaching and learning at a tutorial institute.  

Even if it's a lot of advice it's still just advice not advices. I would suggest a good coursebook with plenty of grammar and vocabulary in it!