I have discovered today that there are Serenity books and comics. I have already seen the series and the movie.
What is the correct order to read the full material?
As usual, my opinion is always that creator's chosen publication order is the best order to watch/read anything. That would mean:
(I don't know of any books about Serenity off-hand, but the comics have been collected into single-issue graphic novels; is that what you're thinking about?)
However, if you want to read them in chronological order, it's a bit trickier: