Help for History NEA structure - Romans

I'm starting my NEA for history with the question 'How psychologically disturbed were the Romans' looking at Tiberius, Caligula, and Nero but I have no idea on the structure or how to explain anything. My teacher is useless for help so come here instead. Also if you have any sources I could use in my essay could you please include them, I feel that all of my sources and quotes have quite weak arguments to them.