Classical singers are expected to be strong actors but are not often given the training required in order to do so. I have found that often times teachers and coaches do talk about the emotional meaning of a song, but tend to assume that it will be enough for the singer to translate that knowledge into a powerful and meaningful performance.
I know many singers who want to get to that next level of performing, and teachers and coaches that want to help singers with that, so here is a great resource: Acting for singers, creating believable singing characters, by David Ostwald.
What helped you become a better singer actor? What book, what teacher, what show? What do you think makes it hard for some singers to act?