It is rude to ask transgender people anything about their past relationships, and you can also talk too much about your past relationships, or compare your dating partners with your ex-girlfriend.
2. Surgery
This is the most sensitive topic in ts dating. No all transgender people have had surgery. Some of them just dress and act as the opposite gender. No matter who are you date with, surgery is a sensitive topic that you should never talk about.
3. Personal information
Don't ask too much about the personal information when dating a transgender person. Safety is often the first concern of online ts dating.