There was a time when oral sex was nice, but a little weird, and I didn't really know what turned me on. Then, I learned how to fantasize, and what to fantasize about! I also learned what kind of tongue action I like! Now, it's rare that I DON'T orgasm when being licked. I'm very sensitive, so I need soft, gentle clitoral strokes--this is part of why it took a fairly long time for me to learn how to orgasm that way, but also part of why oral sex is so fantastic for me now.
My partner, on the other hand, has never orgasmed from oral sex alone. This was really strange to me at first, because I dated quite a few women before meeting her, and had always gotten excellent results in using my tongue on them! But my partner needs strong, hard stimulation, exactly the opposite of what I like, and my tongue can only keep up for so long! Haha. My fingers work much better on her when it comes to orgasms.