Really, the only thing you can do is try to speak at your lowest, but that can sound pretty fake and, therefore, ridiculous. I tried speaking as low as I could prior to getting on T, and had a few people point out that I sounded like an mtf who was just starting to try using a female voice (no offense intended, ladies, just the truth). After that, I pretty much just spoke in my normal voice, which was fairly low to start with, but it was still distinctly female.
Yes, smoking cigarettes will give your voice more of a throaty quality, but as someone who's been smoking for 9 years and is desperately trying to quit, I'd recommend against starting. Unfortunately, the only tried-and-true method of making your voice sound more masculine is T.
SD