The Chicago Manual is a comprehensive style manual used throughout the U.S. publishing world, perhaps more comprehensive than most college students need, but containing much useful advice on matters of punctuation, capitalization, and word choice as well as on the documentation of sources.
Resources "that address questions about using and documenting sources; avoiding plagiarism; writing in the disciplines; grammar, style, and punctuation; and other aspects of writing."
Citation Manager
Zotero: The Tri-College Libraries recommend Zotero, a free online app that can format your bibliography, keep your citations organized, and even save your articles in the cloud so you can access them later from the library, home, or a café.