I'm not really open, but at the same time, I don't try to hide it.
I'll admit, I'm paranoid about people knowing, and really touchy as to who I tell. But I've found there's situations where you really just can't avoid it without getting yourself into trouble.
I've gotten my name changed, changed my gender with social security, and scratched out the gender marker on my ID (can't have it changed without bottom surgery). But throughout that process I had to be out to those involved. And even now I still have to be out to medical professionals and have to explain to companies when I'm changing my information why I'm changing my gender too. And I've had to explain I was trans when I've had background checks run for jobs. And then there are those friends who knew me before and still accidentally use incorrect pronouns or just plain don't have the respect to use correct pronouns...
No matter what you do, you can't be completely stealth unless you get your surgery and leave where you grew up...
I plan to do just that, but I think, during transition, there's no way to be completely stealth.
So in my own way, I advocate. Online, in open-minded groups, through petitions and emails to legislators. There's more than one way to advocate, I don't think any way is wrong. But I, living in one of the most anti-LGBT states in the country, am far too afraid of the people around me to be completely open about being trans. And if at all possible, I don't want to be thought of or treated any differently than my cisgender friends.