13 year old traveling alone from Canada to China

Hi everyone, I am looking for tips for customs and picking a good seat for my flight. I am a 13 year old that will be traveling alone from Canada to China. I am flying from YVR to Taiyuan Wusu with a 3 hour layover in Chengdu. I will be flying with Sichuan airlines. Do you recommend I get the unaccompanied minor service?