Prodigal Son of Tang Dynasty

In the first year of Yonglong of the Tang Dynasty, after the rule of Zhenguan, the entire empire was in a prosperous age. All nations came to the dynasty, and the people lived and worked in peace and contentment, and there was prosperity. As Menghui who traveled through time from later generations, he is well aware of the crisis behind the prosperity, and then the Shenlong Coup, the Wuzhou Revolution, the Kaiyuan and Anshi Rebellions and other major historical events. As a little butterfly following the historical trend, how did he flap his wings and use his meager personal influence to change this period of history?