One of the key points that has come up again and again in books, videos, and from the lips of my teacher, is that YOU MUST READ a LOT! And that means ALOUD!
Much like me using all caps, reading aloud can be very annoying! So if you are doing it somewhere near other people, then the natural tendency is to try to do it quietly, or under your breath.
Since a big part of what you are trying to do is work on your volume and breathing, this does not do a whole heck of a lot for you.
So get out somewhere alone and read something – anything! Ads in magazines are good, articles in the newspaper, or just passages from books.
One note here, my teacher told us to read, but he told us novices not to bother to record and listen to it back yet, because we would either:
1. Fall in love with our own voice and then learn a lot of bad habits and not want to change them later, or
2. Hate the sound of our own voice but not really know how to make it better and get all depressed and crappy and just decide to go back to the security of that old job scraping monkey poo off the sidewalk in front of the cage at the zoo.