I've worked with a lot of actors and actresses, spoken to on-air personalities, taken speech classes, etc. And the one thing I can tell you about that is: Whatever works for you.
I know one actress who swears by slippery elm lozenges. She's 62 and still has a tremendous, buttery-smooth voice. I know an actor who prefers to do his voice work in the afternoon. Others simply drink a cup of coffee to loosen up the vocal cords. Many tell me to stay away from dairy products at least 24 hours before a recording session. Some say gargling with warm salt water is the key (and frankly this one also helps me when my throat is sore).
The key is to protect it. Don't go karaoke singing the night before a big session. Take breaks during a long read. Drink lots of water. And do what works for you and what's comfortable. Your voice will change with age and over-use, so don't expect to sound the same at 50 as you did at 30.
Oh, and don't smoke if you can avoid it. It may make your voice sound deeper, but it also sucks the air right out of your lungs and you wind up speaking more from the top of your chest than the bottom.
My two cents only.