Be friendly to everyone not just to those more senior to you in the organization. It may be difficult to be pleasant and friendly to the company grouch, but it is essential. Lose any precious attitudes you may have about the importance of your own job. Do your share of the grunt work without complaining. And if you really want to astonish people, offer to help before you are asked.
Nobody is too important to make coffee, or wash up a cup.
Don t expect others to be perfect or yourself, for that matter. You know what they say, Good judgment comes from experience and experience comes from bad judgment. So if there are minor screw-ups, and there always are, cut some slack for those around you. This includes the biggie don t start gossip, don t pass on gossip. A simple, I prefer not to talk about people when they re not present, is an effective way to shut down malicious comments.