Encourage your students to use books as well as journals and the Internet. The large number of electronic resources available will tend to steer students toward journal literature, but often books will provide more in-depth information and analysis. Confirm topics early in the process. Specify a particular style manual and your stylistic expectations. Most students are unaware of the multiplicity of style manuals and are baffled by choices.
Papers are easier to grade if all students use the same manual.
Clarify your expectations about paraphrasing, citations, etc. A carefully structured assignment, in itself, will foster creative responses and discourage plagiarism. Structure the timing of the project, and build in a period of response to the information gathered. Incremental due dates, help to break the research process down into manageable stages. Intermediate steps might include handing in a preliminary working bibliography, reporting on a research in progress, and writing an abstract or outline.