Educate yourself on how to use the libraries' catalogs. Most colleges offer brief, simple workshops on how to find materials.
Find out which, if any, online journals you can access from your school's libraries. This might save you a trip to the stacks and some time at the copy machine.
Ask about special database access. Many college libraries allow free access to databases that you'd have to pay to use otherwise.
Find out what specialty libraries your college has. These libraries often contain materials you can't find anywhere else, such as maps, rare books and personal collections of deceased scholars.
Consult with reference librarians when you're faced with a research task. These well-trained, extremely knowledgeable people will help you find resources you never even knew existed.
Ask if it's possible to make purchasing requests for specific items. Libraries often have ways of gathering student input on what they should and shouldn't order.