Like if one person is being aggressive and the other person is just trying to keep up. It's like you're being attacked. The object should be to take her breath away and make her dizzy. Slow has always worked for me. You should never rush the moment.
Hands are important, soft on the face or at the back of the neck below the hairline.
The eyes will never lie. Also, find a stealthy way to moisten your lips before the kiss starts so they aren't totally dry. When you kiss someone the first few times, try a few different things and remember what got the most reaction, or a certain type of reaction. I felt some imaginary yet powerful physical force pulling me towards the person. Another easy cue of when to go for it is when her eyes start darting back and forth between your lips and your eyes.