Perhaps the best way to kill the excitement of a new semester is realizing that one of your professors is not quite what you were hoping for. In fact, he or she might be downright bad. With so many other things to manage -- not to mention a class to pass! -- knowing what to do when you have a bad college professor can sometimes seem overwhelming.
Luckily, even if you're totally stuck with Prof. How-Did-He-Get-This-Job, you still have some options for working around the situation.
See if you still have time to switch classes. If you realize your situation early enough, you may have time to switch to another class or even postpone this class until a later semester (when a different professor takes it over). Check with the campus registrar's office about the add/drop deadline and what other classes might be open.
If you can't switch professors, see if you can just sit in on another lecture section. While this only works for large lecture classes, you might be able to attend a different professor's lectures as long as you still go to your particular discussion sections/seminar. Many classes have the same daily reading and assignments, regardless of who the professor is. See if someone else's lecture or teaching style better matches with your own.
Get help from other students. Chances are you're not alone in struggling with your professor. Check in with other students and see how you can help each other out: meetings after classes? study groups? sharing notes? helping to read each other's papers or lab drafts?
Get a tutor. Bad professors often can lead to bad grades. If you find yourself struggling, get a tutor as soon as possible. And don't be shy about it, either -- would you feel worse asking for help now or possibly failing (and having to retake the class) again later? Check with a tutoring center, your residence hall staff, or any upperclass students about how to find a tutor as soon as possible.
Remember that you have the option of dropping the class -- by the deadline. Sometimes, no matter what you do, you can't make it work with a bad professor. If you need to drop the class, make sure you do so by the appropriate deadline. The last thing you need is a bad grade on your transcript on top of the bad experience.
If something serious is going on, speak to someone. There are bad professors that don't teach well, and then there are unfortunately bad professors who say offensive things in a classroom or who treat different kinds of students differently. If you think this is going on, talk to someone as soon as possible. Reach out to your adviser, your RA, other faculty members, the chair of the department, or even the dean or provost to bring the situation to someone's attention.
Take a moment to see how you can change your own approach to the situation. Are you stuck with a professor who you always disagree with? Turn those in-class debates into a well-researched argument paper for your next assignment. Do you think your professor has no idea what he or she is talking about? Show your mastery of the material by turning in a stellar lab report or research paper. Figuring out what you can do, no matter how minor, in dealing with a bad professor is a great way to at least feel like you have some control over the situation!