Never use "tranny" when communicate with transgender people, it is a derogatory word. As far as I know, it is often used in porn, transgender woman are treated as objects in this way. respect is the first step of every relationship, so if you want to date trans women and have a love relationship with them, please respect them firstly.
Don't ask them questions about transgender
I knew from transgender people that many cisgender people like to ask them questions about transgender in trans dating. I want to mention that it's also rude to ask transgender people some questions about transgender. If you are interested in transgender, and want to know more about transgender people, you can search on Google before dating.