I'm really surprised that my answer seems to be a bit of an outlier here (dress alone suggest cross dressing, additional methods of presenting suggest transgendered)! Maybe it's because I live in San francisco so more people are comfortable dressing or acting outside gender norms here? Not arguing with anyone here, just trying to figure out why my answer seems to be so diff than the agreed response.
I just keep imagining how annoyed I'd be if I went to the store in men's jeans and a men's tshirt, but otherwise looking like a girl, and the clerk called me "him"
Well, but I can't even tell the difference between men's and women's t-shirts and jeans, so in the absence of any other cues, I would look at you and think "female."
It's hard to define "cues," because it's not necessarily makeup; one of the three transwomen I know closely is absolutely not a girly-girl, and the other two are. But you can tell all of them are women. I'm not even sure exactly what combination of characteristics adds up to the perception. In fact I have more trouble remembering to use "she" with the girly-girl ones, because their transition occurred years after I met them, while the more "tomboyish" one was introduced to me as a woman from day one.
So, no, I wouldn't call you he if you wore men's jeans and t-shirt. If you shaved your head and
introduced yourself as "Bob" and
pitched your voice low and
maybe other factors as well, I might think I was supposed to do so.