Warming up your body, breath and voice before doing voiceover work of any type is not optional. It's necessary to prevent vocal strain, improve your articulation and bring dynamic energy to your reads.
You do not need to complete every exercise below. Try several, notice what helps, and gradually develop a short routine that suits your voice and the material you are recording. About 15 minutes is enough.
Warm-ups should feel gentle and comfortable. Stop if an exercise causes pain or significant strain. Avoid pushing the voice when it is hoarse, sore or unusually tired, and seek advice from a health professional or speech pathologist if voice problems persist.
Start with a body warm-up. Vocal performance involves your whole body, and a proper warm-up releases tension and helps you to move during your performance.
A focus on breathing is the next step. Breath is the engine of your voice; warming up your breath and a focus on your breathing will help you to have the breath you need to deliver your performance.
Next, it's time to warm up your voice itself. Resonance, pitch, articulation, all that jazz.