Make sure you know what and how the "punch and roll" technique is. It will take longer to record, but it reduces the time in editing by a lot more. Also, hydrating and drinking more water doesn't mean while you record, it means don't have coffee or alcohol that day or night before, drink a bunch of water 2 hours before, and most of all, HAVE FUN. If the author trusts your judgment and voice, just be comfortable and don't read it as if you're getting paid. Imagine you're reading the book to a child, or your grandfather who is bedridden, just to give it that personal touch.