State your topic in the form of a question.
For instance, instead of saying that you want to do a paper on stem cell research, frame the topic in the form of a specific question, such as:
If you need help forming a question, try reading an article or two on your topic from a scholarly journal (See the "Journals" tab under your subject), searching in an appropriate database and reviewing some of the article titles and abstracts, or skimming an encyclopedia article on the topic.
Some other questions to ask yourself (from QuickStudy at the University of Minnesota Libraries):
STARS Research Guide: