The process of recording an audiobook can be divided into two categories: Speaking and thinking. Plus research.
SPEAKING
1. Don't try to match the author's voice. Shy and pallid people write books that are funny and tough. Maybe they do so because they really aren't funny and tough in person. Match the voice of the character you find in the text. An author told me I'm not sure I sound like me. Probably true.
2. With fiction, you have to give the characters individual voices. Otherwise, just being practical, dialog gets confusing. I associate characters with people I know. As a character speaks, I keep a picture of my friend in my mind. My pal Janet who has an unusual voice, has no idea how many appearances she's made. It is a big help if you are, like me, truly terrible at impersonations.
Avoid stereotypes. Not all old people sound old. My father on his 90th birthday launched into his funny old guy impersonation. Yes, a 90-year-old man was playing a geezer and they sounded nothing alike.
Some writers identify with a particular character. And sometimes they love more than one. It can get complicated when two characters in conflict speak with equal authority. Richard Russo writes separate characters who seem to be different sides of the same person. Cut one, the other bleeds. But that's something the very greatest writers do. It's their mission: They inhabit all their characters and make us see virtue in each one. Readers have to let each one speak.
THINKING
I had good teachers who taught us to respect the text as a unique thing, not as something typical of a genre or period or even of its own author. We were taught to go mano a mano with texts.
Figure out what the writer means to say. Know when the author is staying on message and when he or she is straying. Don't try to repair the text. Forgive the error and continue with conviction.
Find what most interests an author. Or what they can't help but see. John Irving and Jack Vance are showmen, they're running circuses. Anne Tyler and Russo like figuring out how people deal with problems we meet in daily life: a loss, a disappointment, an accident, getting old. But what really interests a writer may be not people but words or scenery or ethical issues. Many readers don't like Updike's characters and the nasty things they do. But nobody denies that he is an amazing observer of small-town American life who writes like an angel.
RESEARCH
Foreign names and phrases: Go to the author or translator. Historians, though, often don't know how to speak a name, they've only had to spell it until you ask. For contemporary figures I go to NPR. (Which, by the way, covers conservative thinkers as well as they do liberals.) Check native speakers, local librarians. You may not find the ultimate authority.
Once in Chinatown I asked the cashier for a correct pronunciation of some names. He called a waiter who in turn called a cook and they couldn't agree. (The three came from different part of Hong Kong.) Persist. Another time I needed the pronunciation of a major English pacifist of a century ago. Charlotte Despard. Turns out there was a street named after her and a pub located on the street and a guy at the pub wrote back to say, yes indeed you do pronounce the final D.
It can be work. But you're getting paid to read great books before your friends see them.