Well its great to know that you are so concerned about your future, but you are just eighteen and you have to be atleast a graduate to appear for the prestigious exam. You need to have a very thorough preparation of the subjects studied at graduation level along with complete dedication and hard work. So I would advise you to first complete your graduation and then prepare for the civil services

Take time to review or self-review days before the exam so you are well-prepared. Remember "Preparation could only take you so far…." Reviewing will also sharpen up your knowledge and will add confidence in passing the exam. It will also allow you to rehearse answering hard and unfamiliar questions.