That is hard to do. I’m not going to lie. Having been there my self, I can give some hints from what I went through, but your mileage will vary, I can assure you of that.
Every person is different, that is sort of a good thing and a bad thing. The good thing is that people are willing to listen on average. My best approach for talking to someone, and outing yourself to them, is do so slowly. Bring up the subject as a nebulous concept to start. “Hey I just say something on a law regarding transgender people passing somewhere and it was good. Don’t you think?” It’s not about you then, but it will let you know if it is safe to take the next step of talking more directly.
With me, it was a month or so of that, and then just getting tired of that dance and coming right out with it one day. With other people after though, I have, because of where I am, be upfront. That depends on you and if you feel safe doing so.
For the reveal, there are sort of two considerations: have you transitioned already and are just outing yourself to this individual that didn’t know you before, or are you going to start transition and you are telling those around you that you will need their support more than ever?
If you are going to tell someone that you have trasitioned before you met them, be careful. Seriously. Just like the first date, go somewhere public, have backup on standby, and don’t let your guard down. This is going to be a big revelation to them, and a change in their world view. People, despite their best intentions, can feel threatened, and lash out with such a change. Make sure that you are safe though.
If you are going to transition and are asking for support, don’t be surprised if they promise it, and you don’t get it. Quite honestly, most transgender people lose contact with many of the people that said they would be supportive fairly quickly Nandi oddly enough the people that are ambiguous are the ones that take up the slack and become the best allies.
I really am trying to be brief, but the question is really more complex than one would think. I believe I covered sort of a base line on that though. Feel free to send a message if there are further questions on the subject.