Yet again, you’ve been passed over for a promotion. As you throw a pity party for one, you can’t help but wonder why. After all, you perform your job satisfactorily—at least, you haven’t received any complaints. You don’t take any more workday breaks or days off than your coworkers. You are pleasant to colleagues, and for the most part, don’t have any conflicts with staff members.

So why can’t you seem to get your career moving forward? You may not be violating organizational policy or dropping any balls, but most likely you are making mistakes—either subtle missteps or sins of omission, or both.

The business world has a lot of unwritten rules and expectations—and the fact that they aren’t formalized doesn’t mean they don’t matter. If your career hasn’t picked up the momentum you’d like it to, it’s time to take a careful look at what you’re doing—or what you aren’t doing.

Having done it all, from opening my own business to working my way through the Wall Street ranks to becoming the CEO of an international financial services company, I have experienced personal setbacks due to ill-advised actions. Here are 10 on-the-job mistakes that I have found may be hurting a person’s career:

Getting distracted from the job at hand. I worked at a demanding full-time day job while simultaneously managing the bar I’d recently bought. Though I was burning the candle at both ends, I didn’t think it was negatively affecting my day job until my manager told me in no uncertain terms that I needed to “get some sleep” unless my career was no longer important to me. Being too tired to do your job well is just one type of distraction that’s detrimental to your career.

Constantly checking your Facebook page, taking personal calls at work, and spending too much time talking to work colleagues are others. People will notice your distraction, even if you think they won’t. Don’t let outside responsibilities or activities—whether personal or professional—get in the way of doing your best work at your full-time job.

Being too patient. Especially in this less-than-hospitable economy, you may feel fortunate to be employed, period. The last thing you want to do is call (possibly negative) attention to yourself by pushing for a promotion, more professional development, higher-level clients, and so forth. I’ll just be patient, you tell yourself, along with the thought: Eventually, the powers that be will notice all the good work I do, and they’ll grant my request.You might be making a big mistake. I caution people against being too patient—yes, even in this economy.

If you aren’t proactive, it’s easy to get stuck in a job that won’t allow you to fulfill your professional and personal potential. Don’t agree to just “go along for the ride” when your own goals and success are at stake. Even now, there are plenty of organizations and jobs out there. If your current employer can’t or won’t give you the opportunities you need to advance, start looking for a job that’s a better fit.

Faking it when you don’t understand something. No one wants to look ignorant or incapable. But a professional setting is nota smart place for a fake-it-until-you-make-it strategy. If you lack the skills to accomplish some project, ask questions. Speak up and find out how to learn the needed skill. Don’t wait until your lack of knowledge becomes a major problem. Make no mistake: People will notice. Early in my career, a client bullied me into saying “yes” to a request I didn’t understand—and it cost my employer $25,000.

While covering up your own ignorance might not come with such a steep price tag, it’s still something you should avoid at all costs. Your integrity, credibility, and reputation—and possibly your job—are all at stake. It’s always better to swallow your pride and say, “I’m sorry, but I don’t understand. I need you to explain.” 

Not being responsive. As long as you check off all the major boxes on your to-do list each day, it’s okay to let a few e-mails slide or to go home before listening to those last few voice mails, right? Wrong! The individuals who didn’t receive a response will remember what theyperceive as dismissiveness, or even a lack of respect. Over time, this can do major damage to your reputation and cause you to be passed over for the most important career-building tasks.

Always respond to your supervisor, coworkers, and customers as soon as possible, even if you have to stay at your desk a few extra minutes at the end of the day. Certainly, never let 24 hours pass before responding to an e-mail or returning a phone call. Even if you’re still looking into the issue, let people know that you got their message, you’re working on it, and you’ll keep them posted. Soon, you’ll become known as someone who is rock-solid and reliable—and maybe even the go-to person in your department or field.

Not continuing to network, even if it’s just within the organization. We all know to network when looking for a job. But when that coveted “You’re hired!” finally arrives, most people cut back on cultivating their professional connections. That’s a mistake. In a perfect world, your great work and dedication will speak for themselves, and the pay raises and promotions you want will follow but in the real world, that’s often not the case.

You need to make a conscious effort to keep your name and face out in front. That means attending office parties and greeting people by name whenever appropriate. You might even take these people out to lunch to pick their brains. And don’t forget to cultivate relationships with people in other departments and even other organizations. You never know where an opportunity might come from!

Not owning your mistakes. No matter how much you know or how hard you try, you are going to make mistakes as you pursue your career. The question is, how will you handle them? I caution you not to follow in the footsteps of a former coworker I refer to as “Never,” who never took responsibility for any mistakes and neverapologized for anything. Never was actually very good at what she did, but her insistence on passing the blame and refusing to admit her errors cost her all of the respect, support, and goodwill she could have earned. Here’s the lesson:

Refusing to own your mistakes doesn’t make you seem more competent. Instead, it reveals cowardice, callousness, and untrustworthiness. I promise, if you’re a hardworking, valued employee, when you do own up to your mistakes, your confession will be viewed as a sign of strength, not weakness, by your coworkers. Plus, you’ll be in a position to learn and improve.

Getting involved in office drama. “But he started it!” “What was I supposed to do, just ignore that nasty rumor?” “I only observed; I didn’t participate!” However you justify your involvement in at-work conflicts, it’s time to step back and become your office’s equivalent of Switzerland. Fighting in the office is a bad idea, period. It makes people unhappy and unproductive, and is a huge waste of time and energy.

Most importantly, it can make others unwilling to work with you. Don’t fight in the office, but if you don’t follow that advice, be sure to follow this advice. Never fight with anyone unless you’re sure you’re going to win. To do otherwise is a form of professional suicide.

Thinking of yourself before your supervisor and your organization. Putting your own needs first is a basic human instinct. But in the big leagues—especiallyif you’re a rookie—you have to prove that you’re going to be an asset to the team, not a drain on its resources or a liability. Often, that means putting other’s wants and needs ahead of your own. Schedule personal appointments after business hours; respond to phone calls and e-mails as soon as possible, even at night, on the weekends, and during vacations; and eat lunch at your desk if there are ongoing projects.

I get that many of these things don’t sound like fun. You might even think some of them are “unfair.” But remember—it’s your job to make your team’s life easier, not the other way around. And when you show that you’re willing to sacrifice your own interests for the good of the team, you’ll have gotten a huge head start on being named employee (or rookie) of the year. Once you’ve established yourself as an MVP, you can start thinking more about your own needs.

Griping about your job. It’s true that this could qualify as one of the greatest pastimes. And sometimes, it feels good to get office-related frustrations off your chest. If you must blow off professional steam, though, I urge you to do it on your own time, to people with whom you don’t work. There will be plenty of things you don’t like about your first (and second, and fifth) job. But complaining about them in the break room—even if you have a sympathetic audience—is never a good idea.

If your comments get back to your supervisor, he or she will think your behavior is unprofessional and wonder why you didn’t talk to him or her directly. Anytime you’re unhappy with something at work, whether it’s your workload, the tasks you’re being given, or how you’re being treated, bring them directly to your supervisor. If you feel that isn’t possible, continue to do the best job you can while looking for a more suitable position.

Bad-mouthing coworkers. Step away from the water cooler gossipfest. Don’t vent about the organization. Don’t gripe about a staff member with the rest of the team. Don’t even make fun of John’s crazy tie, unless he’s right there laughing with you. In fact, this is my personal golden rule: Never say anything negative about anybody in your workplace. Ever. These comments have a way of getting back to the people they’re about.

One of the stupidest mistakes I made in my career was the time I told a coworker I didn’t like a colleague of ours. Predictably, my comment got back to the colleague, and it almost ruined my career. Finally, I became aware of what had happened and I reached out with a heartfelt apology. And guess what? Even if the other person never becomes aware of what you said, your colleagues will still make judgments about your character based on your willingness to bash someone else behind his or her back.

Over time, any of these habits can tarnish an otherwise great reputation and overshadow your accomplishments in the eyes of your colleagues and supervisors. Remember, in the big leagues, your reputation is every bit as important as your skills and experience. Make sure you’re proactively protecting it.