Hey man, what tends to help with me is look for visual cues first. A big indicator that she wants to kiss, is her looking at your mouth, and perhaps wetting her lips (I bet you do the same thing to. I know I do

) So, if you're in doubt, keep an eye out for these signs.
Also, when I am ready to kiss a girl, I make sure that I'm already close to her. Planting one on her from 3 inches away is a lot easier and way less awkward than dive bombing her face from 3 feet away. Try putting your arm around the small of her back, and pressing your fingers in to pull her toward you, and you move in slowly. It gives her a sign, and helps the two of you coordinate so one person doesn't have to lean in all the way.
Hope this helps!