As I'm sure you've noticed, there are a ton of how-to voice-over books out there. Recently, I was doing some tidying up in my storage room and found a copy of "Voice over. Voice actor. What It's Like Behind The Mic." It was stuffed in the bottom of a cardboard box under a table. I had forgotten I bought a copy some years ago on Amazon. It's written by Yuri Lowenthal and Tara Platt--a very talented husband and wife team who are A Listers in the animation voice-over world. What I love about this book is their sense of humor and its easy to understand advice and information about all things voice-over. This book will answer many questions you may have.
In it you'll find:
Ins and Outs of auditioning
Tips for reading copy
How to stand out
How to market yourself--demo production
Agents (Their mindset and getting one)
Union vs. Non-Union work
What to expect when you land a voice-over job
The book is mainly geared toward beginners- intermediate, and it's a solid read.
I highly recommend. You can grab a copy on Amazon. It's 5 star rated by readers and has been updated.
Trends and business practices change quickly in the voice-over world.