If you don't mind, I think I might be able to help by telling you the contrary of what I should do.
-Sound bored. Very bored. Eliminate "excess emotion" from your voice.
-Speak somewhat loudly, and "throw" your words instead of "giving" them. Try to get more of a chest voice; less of a head voice.
-Try to minimise the height variations when you talk (some call this "sing-song talking"). Rather, "punch" words to make intonation differences;
-Don't smile too much when you talk.
I hope it helps at least a little. Apart from that, I would suggest that you look into MTF voice tutorials... and do the exact opposite. Except those that mostly deal with pitch-raising exercices, those are full of tips for the male-voiced MTF to pass better by "decorating" her voice, if I can put it that way. So you should be able to apply at least some of those tips in reverse for you.