I recommend Peterson's Guide to Internships. Keep an eye out for internship opportunities in magazines and newspapers. Check the classifieds. For a fee, they will help you find a place to work, provide you with housing, and usually you will be able to get course credit. Go to your career center at school.
Most schools provide some kind of assistance for finding internships.
Be careful not to limit yourself to what your school recommends. There are many more opportunities available than just what your school will point you towards. Search the web. There are numerous sources out there. I found a few, but this is not a comprehensive list.