For courses in the sciences, one commonly used style is the Publication manual of the American Psychological Association.
You can consult print copies of many style manuals while in the library. We keep them in the reference collection on Level A. You can also use Cite Source, which gives an overview of commonly used citation styles.
Cornell's guide to annotated bibliographies may be helpful.
Disclaimer: always check with your professors about which styles they might require for their courses.