For a book like Titchmarsh, or Iwaniec and Kowalski, it seems a thorough knowledge of asymptotics is a prerequisite.
What are good books for training oneself in such manipulation of asymptotics, bounding of integrals and all that paraphernalia which analytic number theorists seem to be very good at; but is not explicitly developed in these books? In other words, what is a good book for hard analysis?