I think most of all its confidence. If you feel, or at least show that you are secure, just go out there and be you, then even with those that gawk and whisper at the sight of something unordinary, you should be fine. The very first time I went outside fully dressed as a woman, including, and this the part that would be the toughest of all, a stuffed bra (you know I still can't even remember what I had used as boobs, maybe a rolled up sock for each, I dunno, 'shrugs it off', I got boobs now, 'grins') as well. I had my therapy appointment that day and had to walk, several miles along busy streets, I figure if I could handle that then I was good. I just focused on where I had to be, hummed to myself (this has always helped me to keep focused on a task and ignore uncomfortable things around me) the whole way, never looking directly at anyone lest I lose my nerve and start visibly shaking from fear. I felt really good despite the initial terror, I just went out there and did it, I was fine, and the next day (night, since I worked overnights stocking) I went into work dressed the same way and fancied seeing one manager trip and nearly fall into something (the guy was a jerk, so it brought some twisted satisfaction to me to see him look like a fool). Of coarse suddenly coming out at work made working there more than unpleasant, most that used to talk to me ignored me after that, and avoided me like a had a catchable disease and I was abused terribly by the managers which in the end forced me to quit. Work I think of all places can be the worst place to come out to, because you spend many of your days there and that's where you get your income, so push your comfort zone at your own risk. But each day thereafter I've lived my life as a woman even on those days that it brought me discomfort from those that tried to bring me down.
Shopping was always the hard on my nerves because it was at those times that I felt like I was being watched the most. I would just take my time and while inside I was a building readying to topple over I remedied that by staying focused, I'm here to shop, so those that I did know were staring (which I could still see out of the corners of my eyes) or talking about me with another, it may had bothered me but I didn't let it show, acting totally ignorant of their presence. When people act like that they are expecting you to cower, cry and run away, in fact they'd relish in it and laugh their asses off, why I'm don't know, sick twisted amusement I suppose, but at the expense of another. My mom on the other hand, she would get so flustered by it all and sometimes would blow up, like, "What're staring at!?" or something else that would for sure call me out and then put more attention my way (though those that were poking fun got embarrassed), but I continued to stay focused and just told her, just ignore them, its okay, no big deal, so long as they aren't physically attacking me, let 'em have their fun, its not bothering me. And she'd try to back up her outburst, "Well it bothers me! Why do people have to act like that! So what if you're not a girl, what business is it of theirs, why does it matter so much whether they know if you're a boy or a girl!?" I had to remind her that even she had a hard time accepting it at first (and still was then). Yeah, it took some time for things like this to not upset my mom so much. Now she tells me that I am her daughter, and when looking back on old pictures of me she has a hard time seeing how that was even me.
Push your comfort zone (that doesn't mean go out there and overdo it, flash and glam will definitely give you the wrong kind of attention if you still aren't very passable as a girl, subtle is best I think, work your way from there), even if you don't think you are ready for it, two things could happen, but its up to you, go out shaking, looking around, and visibly out yourself (body language is the first sign that people are going to notice), or show complete confidence (even if you aren't) and the end results could be favorable. It all depends on how you handle it. Stares, pointing, giggling, name calling, it can all penetrate deeper than anything, but if you can take it, it can actually help fortify you.