Chicago style is the citation method most frequently used in history.
A quick guide to citing sources according to the Chicago Manual of Style can be found here.
The Excelsior OWL has very good guides to Chicago as well.
Zotero is a free citation manager, and has a website, Zbib, that lets you quickly generate citations. Please see the Zotero guide for more information.
If you are working with physical archives, check out Tropy to keep track of your research.
When using a citation manager, make sure that you proofread very carefully. Citation managers are very helpful, but can sometimes be wrong.
There will not be an example for everything you might want to cite. When this happens, it's important to keep in mind that the goal of citation is to allow the reader to locate the sources you used, so be sure to include all of the information that they would need.
When creating and compiling citations, make sure you know:
Parts of a citation for a book: