I'm having a difficult time formulating a thesis on Rousseau, Locke, Hobbes, etc on state of nature, etc?

Can anyone help me out? I need to formulate a thesis comparing any of these two authors (Locke, Hobbes, Rousseau, Kant, etc). I know the topics I want to cover will either be on the state of nature/human nature, reason, the sovereign, or the social contract...i just can't finalize a good thesis, any help would be greatly appreciated.