You're 13, don't worry about girls, honestly. Just continue doing what makes you happy. There is NO secret to getting women. Sure, there are techniques, but if you're doing that, is that really you? If a girl only wants you for your "game", that isn't good. You aren't being true to yourself or her.
Confidence is the most important thing and the most attractive. Just be you and they will come eventually. Everything takes time and there is a right moment for everything. If it happens, it happens. The more you strive, the more you fail.
I didn't have a sincere lady in my life until I was 18. I tried all the "techniques" throughout Highschool, it didn't work. It didn't work, because I wasn't being myself and you're not confident when you aren't true to yourself. The only reason why I got my first lady was because I was myself. I literally did nothing.
If you think a girl is attractive, just tell her. If she refutes you, then she isn't worth it. If she accepts you, you just won, go adventure with her and share many smiles and laughs. Just be true.