HI,

Here are few books and practices which will definitely enhance your vocabulary:

Word power made easy by Norman Lewis:This book doesn't cost you much and is easily available. It's a must have for anyone who is learning words.

Verbal ability by Arun Sharma:This one is amazing with great possibilities of covering all the 

Read physical newspaper everyday.Mark words which is new to you.Learn 2 to 3 words each day and try to use those words in your conversation.

Read novels of different genres of different authors.This will definitely build your vocabulary as well as improve your RC solving capabilities.

For vocabulary you should be in a constant phase of learning. Read practice repeat.This is the only mantra.

What you do today can build all your tomorrows.:)Stay focused and dedicated.

GOOD LUCK