There are a number of good essay topics that emerge from Act 1 in Julius Caesar. Let me offer two possible topics.
First, you might want to write a paper on the fickleness of the crowd. In the opening scene the people are about to celebrate Caesar's victory over Pompey. This is not problematic, but it is revealed that in the not so distant past, these same people were praising Pompey, Caesar's foe. This shows the lack of faithfulness of the Roman people. One wonders whether the people will turn on Caesar? The role of the crowd or the psychology of the crowd can be a fabulous paper topic.
Second, you can talk about the power of religion. In Act 2, there is a soothsayer. He famously says "Beware of the ides of March." Caesar, of course, does not pay attention, but he should have. Religion is everywhere, that is to say, the gods are real in the ancient world. Julius Caesar, of all people, should have known this, as he was elected as Pontifex Maximus.
Also in Act 3, there is a horrible storm that is not typical. This shows that the gods are not pleased. One may even call it a prodigy within the Roman context. Prodigies, according to the Romans, were one of the way that the gods communicated that something ominous was about to take place. Again, Caesar should have know. The role of religion is also a great paper topic.