Google is a good place to start your research, but here are a few tips for smart searching in google!
Site limiting is simply a command you can give to google which limits what domains it looks for your search terms in. In the screen shot below I am interested in the connections between factory farming practices and infectious diseases. The best place for sources for that is likely going to be .gov websites. So I will limit my Google search using the command site:.gov.
The SIFT Method is by far the best method for researching in digital sources. It was invented by Mike Caulfield of Washington State University, to help researchers quickly make decisions about wether or not a source is worth our time and attention.