Everybody has suggested very very good books there is no doubt.. But i suggest and request who -ever is starting with MOS and BJT circuits you should go first with Microelectronics, Millman & Grabel..it's really a superb book..
My opinion is that you can follow any one book(any of the books suggested in this forum), stick to it, adopt it, understand the concepts by working and re-reading it, revise it regularly, get back to the book every day or any time consistently and periodically. Book you choose matters but it is not everything...