I'm going to be the oddball in this thread. I married my best friend, and I wouldn't have it ANY other way on the planet.

He had an extra ticket to a concert here in town, and invited me to go with. We had been best friends at this point for quite a while. At the bar afterwords, he says to me, "I have something to tell you. I am deeply, madly, and hopelessly in love with you." I then immediately responded that I respected him too much to give him the "you're such a great guy" speech. I was with another guy at the time. I didn't talk to my husband for about a month afterwords, because it was so weird. Then, we ran into one another at a party, and started talking again. My relationship at the time was falling apart, and that helped. We got back to "best friend" status, and about four months later, we were dating. (Actually, we skipped the dating process, and went straight to a serious relationship.)

The biggest thing to worry about here is that she's a high school girl. Teenage girls are especially crazy and insecure, with few exceptions. She may be hanging all over you because she likes the attention. Maybe she needs the reaffirmation that she's a pretty girl, and all that sort of high school insecurity. Chances are, if she does like you, she's probably terrified of making the first move.

The reason I avoided my husband for a month after he told me was because of the manner in which he told me. It was a bit too much and too intimidating, scared the crap out of me. So, don't do what he did. He's lucky it worked out alright. lol (actually, I'm pretty damn lucky, too.)

Instead, go with a more subtle approach to feel out the situation. Take her out to dinner, and pay for everything. Sit down with her and talk with her about what she's looking for in a guy. See if you fit the bill. Gaze into her eyes, and see if she gazes back, immediately looks away, or doesn't notice. If she doesn't notice, then that's bad news. There are ways to lead up to that first kiss which leaves plenty of bail time. Do it slowly, and see how she reacts. For GOD's sake, NEVER ask a woman, "Can I kiss you?". They will almost always freak out and say no. Going in for the slow kiss is often times the best and most honest indicator as to whether or not someone likes you back. She may be nuts about you, and not even know it herself until you've kissed. In matters of love, I've found that it's always better to act first, and talk about it later.