My paternal side comes from Acquaviva, Bari.
The only way I could go through was connecting siblings of my ancestors. All possible branches and lines, because there are small bits of information everywhere, but they are not always mentioned in our ancestors acts.
After that you know you will need the church's archive, that has an incredible amount of information, but to combine it with the whole connections is also a crazy work.
Anyway, I did it and I still need to go back to continue, but it was really an amazing experience.