If you have plenty of time to make notes and scan through various books then try to purchase books which are being used in local engg college (Do not use those books which are being used in IIT or written by foreign authors). Use books of desi writers.
If you are a busy person and have no time to make notes etc. then you can join excellent postal course by AMIE(I) Study Circle. You can download their prospectus at http://www.amiestudycircle.com/