When you are using a new source for the first time--in print or online--look for a "how to use" or "about" section. The information there will help you understand the scope of the resource and how to use it most efficiently and effectively.
Browse the table of contents and/or the index. These are essential tools for navigating print materials but they are also useful with online treatises.
Look for publication and/or supplementation dates to determine whether you need to use another tool to bring the research up-to-date.
When you can't find a citation format for the type of material you want to cite, try searching the law reviews published by the creators of the Bluebook in either Lexis Advance or WestlawNext. Limit your search to articles published after the latest edition of the Bluebook. You might get lucky and find a citation that you can use!
Keep a research log for each project. See Develop the Habit: Note-Taking in Legal Research, written by Gallagher librarians Penny Hazelton, Peggy Jarrett, Nancy McMurrer, and Mary Whisner.
Their top 10 tips (paraphrased) are:
Many Internet sources are here today, gone tomorrow. If the item you find is important to your research, download a copy and save it in a folder on your computer or a file-sharing service like Dropbox or Google Drive.
When is it safe to stop? Generally, when the same cases and statutes repeatedly appear in your results.