13 years old and going on an international flight?~?

Hello! I am 13 and will be going on an international flight from Canada to Germany. This is not the first time I will be going on an international flight because we immigrated from Russia to Canada, however this will be the first time that I will be going on my own, without anyone else. Do you guys have any tips for me? The flight will be about 8 hours long and also I'm not sure what to wear! This would be in August, so what should I wear to the airport? Also do you know what I should bring to pass time? I'm not a sleeper-on-the-airplane type of person, so don't say take a nap. Can I take pictures inside the plane (ex: I want to take a picture out of the window at take-off? Also how do I go through the security? Do I need to go through the security after I land in Germany? Or when I land what do I do? Thank you so much!