Changing from a career as a college student to the dreaded career in "the real world" leaves many students in somewhat of a culture shock.
Many college students have an internship or two under their belt by the time they get to college and I highly recommend that to ease the transition.
Here are some things that you can realize or change as a college student that will help you in moving to a 9 to 5:

1. Change doesn't come easyMost college students come out thinking they will fix everything in a company.
   Keep this attitude but be realistic.
   Even if the way something is done now is inefficient, change is a big deal.
   People don't like to change because they have to re-learn or break a habit.
   There is also usually a bigger picture than you don't yet know.
   Just because it should change doesn't mean it will.
   
2. Connections often trump performanceYou will experience this especially in your job search.
   The easiest way to get a job is not submitting your resume online, but through someone on the inside.
   You are also going to see this in your superiors and co-workers.
   Your superior may not be as qualified or knowledgeable, but they know more people than you.
   Of course connections without good performance backing you up will catch up to you.
   
3. Be a nerd, but with social skillsNerds are not hugely successful, nerds with social skills are successful.
   Unless you invent time travel, how well you can talk to a computer doesn't matter if you can't also talk to superiors, co-workers, investors and customers.
   
4. Keep it simpleMany students try to impress with essay emails or big words.
   Emails should reflect the way you would explain in person.
   Long emails get ignored or skimmed, so keep them short and/or bulleted.
   Don't make me get a dictionary or read a novel.
   
5. Be casual, yet professionalYou will not talk work all the time.
   Share stories to build relationships, but learn what to talk about with different people.
   You won't share the same stories or detail with superiors as you do peers.
   Even with peers it is possible to go to far.
   
6. Use your first job experienceMore than likely your first job is not where you will retire.
   You need that job to get experience, but it doesn't have to be your life's calling.
   Use what you learn to find out what it is you do want to do for the rest of your life.
   
7. Maintain an attitude of innovationWhile this may seem to contradict some of what I said, maintain an attitude of bringing innovation.
   The routine of working can dull your creativity, but people don't get promoted (usually) for consistently meeting expectations.
   Bringing innovation will exceed expectations, so maintain your "change the world" attitude, but don't expect it to happen tomorrow.