Well we hear what we want to hear and the recording device hears the truth

You will simply need to talk and talk and talk and talk some more into a recording device and actually listen to your voice. My advice use your car, no one to listen to you and you can talk loud and clear and get the REAL sound of your voice. Pick a topic that makes you laugh, and pick a topic that makes you angry and pick one that makes you awkward. Be very careful to actually get right into the conversations, become actually angry as if you were debating something.
Our voices are based on what we are saying and why. I'm a damn sight different when I am saying something funny to my wife, than when I am upset about something eh.
But actually making a male voice into a female voice? I would expect your chances to be a lot less successful that your make up and ward robe efforts. Easy to find a dress that looks good than find a voice anyone will believe belongs in a female.