A college professor friend of mine recently asked for the best piece of advice we had ever received as we started our careers. I have gotten a lot of really great advice over the years, but there is one piece of advice from early in my career that was by far the best piece of advice I ever received.
Get over yourself – Be confident, focused, humble & grateful, not cocky and entitled. Yes, you have worked hard and are probably very smart and talented, but there is a fine line before you cross over from being sure of yourself into appearing obnoxiously overconfident. Remember you have a lot to learn about your job, yourself and the world around you. Make sure your employer and your new coworkers know that you realize that and you are open to being taught. No job or request is too small for you. If you are asked to make copies or get coffee, do it. Everyone who is really successful did their time doing the the shitty work too. Embrace it and learn from it.
Most importantly, treat EVERYONE – from the CEO to your co-workers to the janitor to the person at the coffee shop – the same – as if they and their contributions are valuable and you have something to learn from them.
Your attitude and work ethics will get you as far, sometimes farther, then the results you produce.