Talking to people on the subway

I read some stuff online about people being really creeped out when people talk to them on the subway. I’ve had some really awesome conversations on the subway. I talk to people on the subway a lot so it occurred to me that maybe I’m creeping people out. Do you have any tips on figuring out when subway conversations are or aren’t okay?
realsocialskills said:
I’m not entirely sure - I don’t really know how to initiate that kind of conversation. I know what it’s like on the receiving end, though. I’ve had some really good conversations initiated by strangers on the subway. I think I know a bit about it, but not enough to tell you how, since it’s a skill I don’t have.
Here’s what I think I know:
Do not hit on people in the subway. (Some people might be ok with that, but most people are going to find it threatening. Don’t do it.)
And don’t half hit on them. And don’t do it if there’s a reasonable chance that they will think you’re hitting on them. (Eg: even if you mean it innocently, complimenting a woman on a pin she’s wearing on her chest is probably a poor way to start a conversation, especially if you are a man.)
If someone has earbuds in, leave them alone. People often put in earbuds specifically to send the message that they do not want to interact. 
If someone is having a conversation about something deeply personal, leave them alone. (Eg: If someone is having an emotional conversation with a friend about the death of a relative, it is not a good time to try to join in and talk about death.)
Pay attention to who else is in the car. If it’s a full car, talking to a stranger is more likely to be ok than if there are only a couple of people there. If the car is empty, approaching strangers is going to seem like a threat, especially after dark.
Don’t touch them. And be careful about physical distance. If you walk up to someone and stand way too close, hover over them, or sit next to them uninvited on a mostly-empty car, it’s going to seem threatening even if you mean it innocently.
If you intitiate a conversation, make it clear that it’s an offer, not a demand. For instance: “You’re reading that book too? It’s one of my favorites”. Or: “I overheard you two talking about Sesame Street - is it ok if I talk about Sesame Street too?”

If they seem uncomfortable, back off.

That’s what I think I know. Do any of y'all know more about how to have conversations with strangers on the subway?