If I’m actor, can I use the same voice I use for acting for voiceovers?

Absolutely! In fact, your actual voice—the one you use every day--is your truest voice, and the one casting directors and buyers want to hear most. Please check out Julianne Grossman's smartactors.com voiceover class for an in-depth look at commercial voiceover, as well as voice work for Animation and Promotion/Narration.