I think, combination of both is the optimal way of preparing for IELTS. Self-preparation without proper guidance might not give you the desired result as you can not evaluate yourself. Perhaps, in some cases, you can assess your progress in Reading and Listening by attempting a test in the book and checking your score which is provided in most of the books. However, it is an arduous task to evaluate your writing and speaking tasks.
The IMPACT IELTS institute in Faridabad can provide you proper and step by step guidance to help you obtain the desired band-score in IELTS. Training is conducted by a very qualified and CELTA certified trainer from Cambridge English.