Generally, most employers now favor softer skills like communication, negotiation and ability to work effectively in teams, for various reasons (greater labor participation for women, the educational system's shift toward types of learning catered to women, etc). This means that if you have stellar "hard" skills such as coding, but you're a loner or shy or have a hard time communicating, you are at a great disadvantage in the running for many jobs, especially in more customer-facing roles. These days, everyone internally (not just outside the company) is considered a client. Make it your first priority in your new job or role to understand with as much detail and precision as possible what it is that your boss expects, what deliverables need to look like, how progress is tracked, what is the big picture and what are the components of the project, in what order.
Do your best to under-promise and always over-deliver!
Tack your own progress in granular detail (keep a notebook!).
Write up your progress weekly for your boss in an email. Cite numbers and figures as much as you can, including percent completion, if possible. Your manager can then more easily report to his or her boss on your progress with tangible figures and make him/herself and you look good and well put-together as reliable. Remember this rule, since it applies generally for your résumé and other places. It's not always the most relevant thing, but management works this way, for better or worse. Adapt. --
Always be selling yourself (not as bad as it sounds... Read on). Read Daniel Pink's "To Sell Is Human" to understand why you have no way out of selling yourself these days. He's really onto something. You're your own best salesman/woman or otherwise your own worst liability in image. In the age of LinkedIN, Facebook and The Age of the Virtual Image, your profile - your proverbial best foot forward - is an essential and inextricable part of your identity an travels with you everywhere you go - into job interviews, first dates, networking events, etc. It's a brave new world where you can't hide from the 24/7 Google radar. Embrace it and make the best of it!