1) Find a private place.
Unless both of you are out as lesbians, a girl probably won't be comfortable kissing you in a public, or even a semi-public place, so you want to keep this between the two of you for the time being. Almost everyone is more willing to try new things when no one is watching.
2) Make physical contact.
Try touching her hair or jewelry and tell her you like it. This a somewhat sneaky ways to get close to her. You could also graze her arm or shoulder gently. As you're talking, keep making physical contact. Lean in or move your body closer to her as you speak, but only continue if she seems open to your advances. If she tries to make jokes or moves away, stop immediately. You may be going too fast.
3) Make her comfortable.
Put her at ease, and try to make her feel comfortable. She may want to kiss you but she might be scared about it at the same time. Act casual, but not too casual. Make sure that she has some hint that you like her as more than a friend. If she seems nervous at all, calm her by asking, "Are you scared?" If she says she is, tell her not to be, and give her a little hug and let her go. If she says "A little," ask, "Of me?" If she says no, you should then move closer to her.
4) Move closer.
Nuzzle into her a little, but if she tries to move away or squirms, back off. If she nuzzles you back or returns any kind of affection, then look at her. If she is gazing back at you, check her mouth. If you see that she's looking at your mouth, she is definitely ready for your next move. Reach under her chin and gently tip her face up so that you can look at her.
5) Have a memorable first kiss.
Kiss her gently at first. That doesn't mean you have to make it a chaste, boring kiss though. Part your lips slightly, making sure they're kissable and soft by licking them slightly. When you kiss her, hold her and make it sweet and romantic. If this turns out to be your first kiss of many with this girl, you will both have fond memories of this moment, so make it count.
After you kiss her, smile. If you both liked it, you can do it again... and again. You can also give her a hug and cuddle together. Before you decide to go further, be certain that you're not starting something you're not willing to finish.
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