So there's this girl in the youth orchestra I'm in. I'm 16, she's 13. I once walked towards the 4-girls-group she's standing in in the break, which is how I came to know her. Afterwards we didn't have any contact for a long long time. [/backgroundstory]
Now she's smiling the absurdely biggest smile I've ever seen whenever I walk past her or whatever, usually companied with a "hi!" (then walking quickly past me). Now she's also sometimes rubbing my hair. Reminder: I'm 16, she's 13.

So my suspiction is that she's in love with me. And she's actually well developed (like Mikuru Asahina, I guess?) ánd she's the first girl in a long time to show interest in me, so I decided to give it a go. Problem is, I usually really mess up with girls, and I don't want to mess up this time. I haven't had a girlfriend for 6 years, so no experience there.

I'm looking for some beginner's advice, and any suggestions or comments about this situation would be nice too. Thanks for reading.