Start work on any large thesis as soon as possible. Many students have papers or projects relating to their majors that must be completed prior to graduation. By starting far in advance, you not only reduce your stress over the course of the semester, but ensure that you've given yourself as much time as possible to create the project.
Prepare your resume and start the job search before you graduate. The job market can be tough, regardless of what field of work you plan to enter. Better your chances of ensuring a job by creating a top-notch resume that looks professional and is filled with excellent references. The more interviews you can set up prior to graduation, the more likely you will secure the position you seek. Even if you don't get a job right away, you will develop better interview skills with each appointment you make.
Make new friends and strengthen your existing college friendships. The social component of college can be just as important as academics, and you can develop lifelong bonds. Go out of your way to reinforce relationships you have made at school, and don't be afraid to introduce yourself to new people outside of your social circle. Make plans to see old and new friends after college ends and be sure to follow through.
Take advantage of your campus resources and try a new club or hobby. Your final semester at college may be the last chance you have to explore such a wide range of facilities and resources. You may discover a hidden talent or interest you never realized you had before. Even if your efforts do not result in any major changes to your interests or hobbies, you can at least say that you explored all your opportunities while you had the chance.