The style and formatting you should use depends on your audience, your discipline, and for assignments, your instructor.
For help writing or picking a style, ask your teacher, your librarian, or the Writing Center.
Explanations of some popular styles in the sciences:
Chicago Manual of Style
Online version. From off-campus, you'll need your NetID.
Publication Manual of the American Psychological Association - style used in many science disciplines.
Paper format only Call number: UM Reference / BF76.7 .P83 2010.
GSA Style Guide - Geological Society of America
The ACS style guide : effective communication of scientific information.
American Chemical Society - book in the Science Library
UM Science Reference / QD8.5 .A25 2006