I was in a similair situation for awhile.
You can be really funny all the time. That's fine. But confidence is the key. Now, my problem was that I was confident in that I know I'm a really funny, smart, cool guy. That's the kind of confidence that makes everyone want to be your friend. I have that down pat.
The difference is having that kind of confidence that makes a girl want to be with you. The things that make girls want to be your friend and the things that make them want to be your girlfriend aren't THAT different. You just have to have the confidence to approach a girl as a potential girlfriend rather than just a potential friend. Your conversation with her is centered around the fact that she's a girl, not just a person, but a woman.
Here's how I do things now. So say you meet a girl and you're doing the whole "funny guy" thing all night. If you thing she's digging you, pull her away from the group to have some time alone in there (hey, girl's name, come here. Let me ask you something). Make sure to get her number THAT NIGHT. Even if you're sure you'll see her around again, that doesn't matter. Get the number before either of you leaves (and don't wait till she's walking out the door. Get it when things are going well and you have her alone, assuming you're vibing with her).
Make sure that when you get the number she understands you want it because you will be calling in a few days to set up a date.
That's it. That's how the funny guy makes it work.