Many voice actors do exercises for their voices so they won’t strain and will sound the best. They do these exercises so their voices can be flexible.One of these exercises is to not sound like you are reading off a paper. Reread and let the words flow out. Try to make your voice sound like how you would imagine the character to sound like when reading your lines. If you feel like this character is cheerful or happy, try and sound cheerful and happy. 

   This isn’t much of an exercise but I do suggest drinking water, drinking water is very useful. Not only will your voice strain/dry out you won’t sound that great if you don’t. Fried food, caffeine and dairy products are foods that you would want to avoid. Butter and soda as well overall you have to take care of your body. Some of these exercises are also used by singers, actors and just about anyone who would be seen online for the world to see.

https://www.voices.com/blog/vocal-health-tips/#:~:text=%5BInstead%5D%2C%20you%20can%20have,voice%20clearer%2C%E2%80%9D%20advises%20Susan.