Well, it would be useful to know your age! If you're old enough I would definitely give a try to online dating. First, (if you want to, and I personally believe would be a good idea) you could say you're trans in your profile. That would probably diminish the amount of people who contact/reply to you, but those who do would already be aware of your transition and would most probably be okay with it. In short, that would help you avoiding awkward situations where you meet a girl, you flirt, you like each other and stuff but then as soon as you tell her about you being trans she leaves or you find out she's not okay with it. So definitely give a try to online dating if you're 18+ and be very careful. Choose wisely who you meet and always make sure you meet them in public (you never know who hides behind a screen until you meet them in person). I would suggest Tinder and OkCupid. On OkCupid when choosing your gender you have a lot of options, including trans-man. Another way if you're 18+ could be parties but you know, you would have to find a girl, talk to her, and spend a lot of time. In the same amount of time you could talk to 10 girls online who are already aware of your gender identity, so personally I find online dating easier and more efficient. If you're younger then you could join some clubs, maybe go to trans meetings in your area/city, talk to girls you like in school or friends of friends.
Dating can be a pain, but take it as a game. Try to be confident and be yourself. If you like a girl go and tell her. Yes, you might get rejected: so what? I know it's a little awkward and disappointing at first, but you'll get used to it!