Certain secondary sources are designed specifically to be finding aids -- examples of this are the Canadian Encyclopedic Digest (CED), and Halsbury's Laws of Canada. These tools are unique to legal research and are great places to start your research.
The CED and Halsbury's are both large legal encyclopedias that address key elements in all areas of law, with abundant citations to relevant case law and legislation. The CED is located in Westlaw Canada and Halsbury's is part Lexis+. Both can be searched, or preferably, browsed, which allows you to see how various subtopics fit together.
Legal dictionaries define legal terms and common words with special legal meanings.