Im looking for help to continue my research

I have been researching my family tree for a few months now, and I have reached a point where I don't know where to go. I found a relative named Angelo Marfisi who is listed in a census in 1786 in Patrimonio, Corsica. He was 60 years old, so he was probably born in 1726. I don't know where he was born, and for those years I don't know where to look because I understand that the civil registers in France were in operation around 1790. Added to this, Corsica belonged to the Republic of Genoa until approximately 1760. What should I do? What do you recommend?