Yes, it may be possible to prepare IELTS on your own if your English proficiency is really good and you are equally proficiency in all the four skill areas viz; listening, reading, writing and speaking. If you are planning to prepare on your own, we strongly recommend to enroll in the following online course:
IELTS Academic Test preparation
This preparation course offered as a MOOC (Massive Online Open Course) course offered by The University of Queensland is a comprehensive, self-paced course covering listening, speaking, reading and writing.
In order to participate in the course, you will need to create an account and enroll in the course. Once you have enrolled yourself in the course, please check the option to audit the course so that you do not have to pay for the online preparation.
Since, it is an asynchronous online IELTS preparation course, the online lectures are recorded version instead of a live version. Instead of no preparation before taking the actual IELTS test, it is better to take the online course in the edx.org. However, we strongly recommend you to join our online or face to face IELTS preparation so that you can get a personalized training to improve your scores in the writing and speaking sections even if your English proficiency is good or you believe that you can excel in the IELTS test.