These questions can be quite discouraging due to not knowing exactly what to do next to bring yourself closer to that special someone.
There are, however, a few key steps and signs that we can watch out for and do to increase the probability of bringing ourselves closer to that special someone.
For guys:
When you're out with a girl on a date and you and her walking around or just talking, you have to understand that you're the one who has to make a move! Girls are told by society that they have to be passive and receptive (not as much after shows such as Sex and the City). Thus, she is expecting you to take charge in escalating the touching that will eventually lead to a kiss.
When you're out with her, be the first one to take her hand! Taking her hand is the first step towards bringing yourself closer to her. If she's comfortable, you can escalate non-intrusive touching a little later, such as touching her shoulders or hugging her. As you progress doing this and watch her grow more and more comfortable with your touch, you have much better chance of kissing her successfully, rather than just going for the kiss out of the blue. When you built this kind of touching comfort, get her and yourself into some sort location where two of you could either sit or stand and talk comfortably. As two of you talk, start stroking her hair softly and look into her eyes. If you feel that she's comfortable with that, move in closer and closer. If she doesn't withdraw, go for the kiss, since if she's comfortable with you touching her hair and standing so closely, most likely at that point she already wants to kiss you anyway. If she withdraws or acts weirded out, relax for a bit and continue building comfort with her. Resume normal conversation and try again later.
For girls:
Usually girls are viewed as the ones who are kissed, rather than the ones that kiss. It's really a matter of personal preference and personal set of beliefs as to how you want to go about this.
Most guys are very shy about kissing a girl for the first time, so you might try to make him feel comfortable by accepting his touch or even initiating non-intrusive touching yourself, such as holding his hand or hugging him and being close to him. If he feels like you're accepting him and enjoy his company and being close to him, he'll most likely go for the kiss.
If you want to kiss him, it's going to be rather tricky, since some guys might feel you're too aggressive to hang out with. If he's super shy, you can simply tell him you want to kiss him, and let him kiss you. This way you preserve his male ego and still get kissed :)
For both:
Kissing should be light and bring pleasure to both partners. Don't rush too fast and start shoving your tongue down his or her throat. Just relax your tongue and softly touch your partner’s lips and tongue. Just barely touching, almost sliding. The kiss should feel light, yet passionate. As two of you get comfortable kissing, you can progress to more aggressive and deep kind of kissing, such as French kissing. French kissing is essentially the kind of kiss where there is lots of tongue and sucking action.
Conclusion: Just let if flow and let it come to you naturally. Build touch comfort over time and when the time is right, try to move closer to your partner so that the kiss can naturally happen. Visit Kissing tips, advice for more information.