Some brilliant acting truths observed in this article gleaned from many decades of acting experience. We particularly love the advice: "Never relax, and mean what you say." (which is actually originally attributed to the great film actor, James Cagney) ; and from the wickedly witty Miriam Margolyes, "The most important thing is to breathe. If you stop breathing properly, you get a sore throat. And if you stop breathing, you die."
By the way, while these are all great "stage" actors and not all of their tips are applicable to voiceover, the ones that are, are well-worth noting and absorbing.
Guardian UK: "Cast to the performers' strengths. I've seen amateur directors pander to the ego of the cast member with the strongest personality. Bottom the Weaver in A Midsummer Night's Dream is Shakespeare's warning from history: he says he can play lions and lovers and everything in between, but he can't."