Thanks for A2A,
My personal choice is Universal Self Scorer but any other book containing complete set of previous year questions topic wise will be equally good.
No matter which book you choose,solve that same set of questions several times and practise that much that you start solving questions in less than a minute.
Quoting Bruce Lee:I fear not the man who has practiced 10,000 kicks once, but I fear the man who has practiced one kick 10,000 times.
All the best!!