For me it was studying other women, walking/speaking patterns. I did this every time i went out, and with it improved my response in those fields.
However; I also had many female friends in early transition who would help me with posture and walking and body language. But try not to mimic, let a bit of you shine through - being feminine comes in many ways, I personally think the best way to display femininity is to be subtle.
Doing small things like taking smaller steps when you walk, talking with your hands but not too much, looking around or taking in your surroundings, smiling xD
Think of it as a safari lol in order to become the woman you must first understand the woman by observing the woman's behavior xD
Side note: theres a chance that hormones might bring out a natural feminine behavior in you (dont know if you're on HRT or not, and this is not to say that its for sure) because since starting HRT, my reaction to things has been different than before in both vocal and body language response. Sometimes that push of empathy causes you to change slightly in your behavior. But this doesn't happen for everyone ~ it happened to me so it could happen to you too :3 I didn't learn my mannerisms or body language from my female friend or from watching other girls at the mall, it kinda just "came out" as time progressed; according to my wife (who is sometimes blunt >_< ) I am "such a girl -_-" lol but she's always been a tomboy so its to be expected lol. The only thing I was able to learn from observing other women was the walking and the speaking.