I found that posture is a big thing. Men tend to hunch over. Women tend to stand straighter. I have to consciously remember to drop my shoulders, suck in my gut, and stick my tits out. It is getting to be more natural.
I am working on my voice. I took some voice lessons last year. The target female range is about an octave above my male baritone. I quickly discovered that there was no way I could sustain that pitch without wrecking my vocal chords, but I was able to manage to get it a fifth (a musical interval equivalent to half an octave) up. It is going to sound like a deep contralto, but it can be convincing if I keep practicing whenever I get the chance. This summer, I did an hour-long public presentation and managed to keep my voice in that range for the entire time.
Men tend to avoid eye contact. Women avoid eye contact with men, but will make eye contact and smile among themselves. As a woman, you are now a member of the club, and the eye contact and smile are like the secret handshake. Avoiding eye contact or conversation is male behaviour.
Especially in the washroom. You don't have to get all chatty in the ladies' room if you don't want to, but it is acceptable, even expected, that you say "Hi" to women in there. I found it a bit disconcerting when someone in the stall having a pee was continuing to talk to me while she was doing her business, but apparently that is not uncommon.