Have you taken the IELTS before? If so, what were your scores?
I would suggest you start by running through a number of mock exams. This should give you a general feeling for what your reading and listening scores are. Continue to engage mock exams regularly and actively note language points that are new to you.
Arrange a speaking partner. Brainstorm potential IELTS questions and practice role playing the exam experience with this partner. Record yourself. Note any areas of hesitation, unnatural pausing, issues with pace, repetition or stuttering.
For writing, the fastest way to improve is to have some personal guidance. If you have a native English speaking friend, have them check your writing samples every few days. Actively note the grammatical changes they suggest for your writing. Be sure to follow a structure and to link your ideas using cohesive phrases.
As you can see, it is important to weigh your progression and become familiar with your strengths and weaknesses. The above routine will help you establish a feeling for how you are going to perform in the exam, and this can do wonders for your confidence.