What's the focus of you research? What are you focusing on? The library can help you choose an interesting and focused topic. Once you have a topic, do a preliminary search to see what you find, then narrow your topic based on what turns up.
Next, you want to pick where you're going to search. Pick multiple options - specialized databases, Google Scholar, library databases, etc... Think about your topic and where you'll find information to fit the different sub-topics related to your research.
You can consult with a librarian to help you develop keywords and search strings, use subject searching and filtering to your advantage, and track down full text of sources.
Make sure you're capturing multiple perspectives on your issue or topic, not just a narrow view. Evaluate your sources carefully for credibility and relevancy.
Make your reading an active process by highlighting and taking notes. Consider using a matrix to organize your sources and identify scholarly conversations.
Remember that your voice has a place in this conversation. Your analysis and organization is the glue of the lit review.