Tips on approaching girls?

Hi there. I used to be a very shy guy some time ago. I still am shy, but not that much (I couldn't help looking a girl in the eyes, now I can do that and smile, even though I'm still nervous!). Thanks to 2 girls I met, which is the main reason I'm more relaxed now, I learned how to be myself, stop caring about what others think and discover a hidden talent: my humor. When I told one of them it was the first time I made a girl laugh, she responded that she couldn't believe it and that I was one of the funniest boys she knew! So I kinda improved on my social skills.

I still have a problem approaching girls though. I try to speak to as many girls as I can as 'practice', both attractive and average, but I can't help it with girls I don't know, although I think that my change has attracted some girls. I freeze when I start moving towards them and stop, because I don't know what to say. I always am myself, but sometimes, even if I get to approach them, either I can't be funny (mind gets stuck!) or I can't project as much confidence as I was.

About my 'dating' character. I'm not the bad boy obviously and I don't wanna be one. I like being kind to girls, romantic and sweet, but I think that at the same time this is a flaw and that girls don't like it as much as I think because they always go for more 'dirty' guys. Do you think I should change something in my tactics? I don't mean becoming a bad boy, I really like being myself. Thanks!