Any company with more than two people in it will have politics. The bigger the corporation the more complex. Your ability to advance in career will depend on your ability to navigate the politics as well as on your technical competency. By the way, I define 'politics' as all human interactions beyond the strict technical requirements of your job.
At the lowest level keeping your job depends almost entirely on your technical competency, at the highest level it is almost purely politics. Be thankful when you reach a level where your personal skills are worth more than your technical ones, because now you are at managerial level (along with the higher salary that comes with it).
Make as many friends as possible. They will always come in handy. Always.
Don't make enemies. You will meet people that you personally loathe, but stay civil because this is just a job, not a marriage.
If somebody chooses to make an enemy out of you despite your best effort to appease him/her, then you have to fight back smartly if you still want to keep your job.
At the end of the day everybody is replaceable. Never get into the mindset that you are indispensable.
With very few exceptions you should not be surprised if you get fired. If you are paying attention to the company's business condition and the behavior of your coworkers and bosses, there should be no surprise.
If you lack the ability or willingness to play politics, make peace with the idea that you will spend the rest of your career at the bottom of the corporate ladder. If you can't accept it, quit the corporate world while you're still young enough to do something else.
Perception is reality. How you and your job are perceived by others is reality to them, what you think about yourself means nothing to them. Build a reputation as somebody who solves problems and gets things done, yet is easy to work with.
Learn to recognize good bosses from bad ones. They all use you to advance their own career, but the good ones bring you along for the ride.
With few exceptions you can't change your boss. If you happen to work for a bad boss, plan your exit then execute it. Putting up with him will ruin your life professionally and personally. Needless to say the same goes for a bad company.
Make sure your boss doesn't get any bad surprises, because if he does he will have few options other than to blame you completely. If you have a problem meeting his expectations (deadline, scope, etc.) let him know in advance. He needs the advance notification to get more help or do damage control, because his reputation is on the line.
On the technical side: most corporate desk jobs involve MS Excel. Intimate knowledge of Excel that includes its functions, macros, and VBA has the potential of greatly reducing your manual workload. This is valuable because it enables you to handle more work, thus setting you apart from the rest. If you want to kick it up another notch, learn everything there is to know about Access.