If you had to go back to the late Ming and early Qing dynasties, what would you choose to do?

Be an idle king. Since the emperor can be a carpenter, the prince likes some strange skills, and it is also possible to get some local xx (gunpowder glass for ironmaking and oil refining). There is nothing wrong with ordering more potatoes, sweet potatoes and corn. Promote toilet farmyard manure or something. (I don't know if the farmers realized it at that time) The land is rotated to grow soybeans or something. Ripening immature fruits with ripe fruits. Wait, something that can be promoted. You can also engage in Ponzi schemes. (I'm too lazy to check the age of Ponzi scheme, I don't know if it will steal his thunder) Then I'll find hundreds of children to raise and teach them everything I can remember! If we are lucky, there will be no foreigners in the inventions and discoveries defined by various theorems in modern history.