In writing a research paper on moral issues and theories I

In writing a research paper on moral issues and theories I have narrowed down my subject to Kants deonotolgy verses maybe Mills Utilitarianism. But I need assistance in narrowing down a topic?
I am leaning towards something like the different veiws on lying, cheating, maybe suicide. Could a whole paper consist of one of these subjects, or should i somehow apply all three? please help I am stuck and short of time. thank you