I still believe confidence and personality are absolutely key here, just like they are for cis guys.
Yes, women usually like penises, but out of everything that attracts to them to a guy, the penis itself is probably pretty low on the list. Most women are attracted to personality traits, the way a guy relates to them and makes them feel (this can differ widely, of course, from the women who like a guy that makes them feel like trash to the women who truly like the guys who make them feel like princesses), and a variety of physical qualities (big blue eyes or a nice smile or a strong upper body or, for some but probably not most, the size of the penis).
Overall, I'd venture to guess that the average woman would rather date a self-assured, sexy, dominant trans guy than an insecure, awkward, submissive cis guy. If you truly and unequivocally view yourself as a man and act like one, chances are that she'll see you the same way.
I haven't tried this myself yet (because I am not far enough into transition), but when I start consistently being read as male and when I have a prosthetic or strap-on to use for sex, I'm just not going to make a big deal of it. I'll probably end up saying something like, "Well, I was born without a penis, but I have an awesome replacement that'll blow your mind if you give me a chance. Couldn't hurt to try, right? Or could it?"
Haha, and if she wants to try, then great. If not, whatever. It'll be her loss. And in my experience so far, that's exactly the kind of attitude that any guy needs; a man that is confident enough to not care if he loses you and is more than ready to move on to his next conquest if you turn him down.