Versatile Voice-Overs that Sell
Voice-Over Books
There are a lot of books out there about getting started in the
voice-over business. Here are a few that I've read recently:

The Art of Voice-Acting (3rd ed.) by James Alburger
     Pretty much the "standard textbook" of VO these days.

There's Money Where Your Mouth Is by Elaine Clark
     Probably pays the most attention to VO acting techniques

The Voice Actor's Guide to Home Recording by Jeffrey Fisher
     Lots of great instruction for home-based VO talents

VO: Tales & Techniques of a Voice-Over Actor by Harlan Hogan
       Helpful advice and fun insider stories about the business!

How to Make a Million Dollars With Your Voice by Gary Owens
and Jeff Lenburg -- Not as much instruction, but a fun read!