like the nike commercials say "just do it!" no better way to learn than to go out and use your voice. I did NOT sound like a woman before but I am consistently ma'amed on the phone now. Then again I am full time
If you want to find your voice? Go full time, you will find it in a hurry! I think my voice comes from a life as a singer and probably most voice coaches will teach you the same thing if you want your voice to sound real and not straining for a falsetto.

1. In singing you should always sing from your diaphragm. You dont want to do this when speaking in a female voice. Speak from the top of your thought in order to cut out the deep resonance of your male voice.

2. In your normal octave sing a major scale. do, re, mi, fa, sol, la, ti do. I put la in bold parenthesis because this is the pitch you should be using. This leaves your room to go up and down with voice inflections. This is all done in a range you are already comfortable with because it is in your range. You will not sound like a squeeky fake.

3. Now practice singing words while holding that note. It will sound silly because you will have no voice inflections, but you have to get used to finding it and holding it before you can ad conversational inflections.

4. Practice speaking in normal conversation now with this note and inflections.

Practice, Practice, Practice

I hear so many girls sound so unnatural, its important that you do not use a falsetto. It will out you faster than bad makeup.