Preparing research papers can be tough; citing them can be tougher, especially with different citation styles. APA, MLA, Chicago Manual of Style, oh my! Do I have a resource for you! Check out Purdue University’s Online Writing Lab (OWL). This was my go-to resource after having returned to graduate school after a twenty year absence from college. The link above takes you to its home page; once there, you can click on “Research and Citation” or click here. One of the reasons I like this site is it explains the difference between the three (3) most commonly used citation styles: APA ”(American Psychological Association) style is most commonly used to cite sources within the social sciences;” MLA “(Modern Language Association) style is most commonly used to write papers and cite sources within the liberal arts and humanities;” and Chicago Manual of Style. Remember to always use the style your instructor has requested in the syllabus!
Another part of the site I like is the individual “Formatting and Style Guides” under each citation style. Screen shots are given of how certain parts of the research paper are supposed to look using that particular citation style. 
For example, in-text citations, footnotes and endnotes, reference list, and an actual sample paper. Check this site out, and refer to it often!