Lots of great stuff here already, but as a corporate executive in charge of R&D, I'll put in my additional two cents worth...
The first rule of business: don't take it personally. It isn't all fun and games. You're not there to make friends or have fun - you're there to do a job. Yes, ideally, on the whole, you should enjoy it - if not, you're in the wrong line of work; but there will be times that the job sucks ass no matter where you work. There will be assholes that rip on you, rightly or wrongly. Don't take it personally. Keep your spirits up and focus on the work at hand. This will get you way ahead of the rest of the crowd.
Act as though time is of the essence - it is. You'll be amazed at how quickly you go from being a green kid out of college to being an old geezer like me. Don't waste your time on piddly bullshit. Work your ass off at all times - not for the company's sake, but for yours. Your life is ticking away by the minute - the only reason it doesn't seem that way is because you are young. Youth is wasted on the young - the sooner you understand why, the better off you'll be.
Don't be afraid to make mistakes. Take on the hardest work you can handle, then ask for something even harder. You don't grow by taking it easy; strength comes from adversity, not comfort. If you're comfortable, you're dead. Ask for help when you need it - there is no shame in admitting that one is in way over one's head; real achievers always are.