Put your hand on your upper chest. Speak naturally, then slowly try to speak further down your throat, so to speak, until you can feel your voice in your hand. This'll take a fair bit of practice, but after a bit it should come pretty easily. Speaking from your chest (or deep in your throat) will make your voice lower--perhaps not as deep as the average cis male, but deep enough to help definitely. It helped me a lot when I was pre-T, to the point where a fair number of the few people who knew about me being trans thought I was already on T.
Good luck, hope this helps!