Check out Cornell’s Legal Research Engine! Simply type in the area of law that you want to research (ex. environmental law) and it will pull up a list of links to research guides on that subject area from different law schools.
Research guides will help you determine where to start researching for the best information on a specific area of law, often listing the most important primary and secondary sources and telling you where/how to access them.
Don’t start from scratch when the work’s already been done for you!