1. Being too political.
We all know about office politics but when you play into them too much, you begin to be seen as more of a politician than a worker. Your co-workers can get jealous of you and start to dislike you if you're being "too nice". People in today's working world are looking for transparency, openness, and genuineness. If you're too political managing your relationships, people will think you're a phony or you're trying to cover something up.
2. Multi-tasking too much.
If you're working on too many projects at once, you end up not accomplishing much at all and losing focus as to what your true priorities are. Employers are looking for people who can prioritize tasks and meet deadlines. Even in a meeting, you shouldn't be on your cell phone answering emails. You should be paying attention to what everyone else is saying, responding with your own advice and perspective when appropriate.
3. Complaining about work.
Whether you're in the office or online tweeting, you shouldn't complain about work. If you dislike your job or your manager, you don't want any other people to know because it can get back to your managers in a hurry. Instead of complaining, figure out aspects of your work that you dislike and try to improve them. Work with your manager to connect your talents to different projects that are important to the company.
4. Making promises you can't keep.
Sometimes you need to say "no" to some projects because if you take on too much, you won't be able to deliver. Don't make commitments or exaggerate your ability to do work or you risk losing credibility and people won't trust you. If you know you can't handle a certain project, speak up and tell them as soon as you can. We are all human and people are understanding of others' situations.
5. Pretending you're in charge when you're not.
I see a lot of employees, especially younger ones, acting like they are executives when they are entry-level. You need to know your role and not overstep your bounds because if you do, it's easy to way lose support. You have to earn people's respect over time and that's why it takes years to build a career, not days or weeks. Eventually, you will be in charge, but today respect the status of others and know where you fit.
6. Focusing all your attention on your job.
If all you do is your job, you won't be able to get ahead. You have to constantly deliver above expectations and make a case to expand your role and responsibilities. If all you do is have lunch with your group and avoid everyone else, you're making a major mistake. By networking with those outsides of your group, you become more valuable, more connected and you might even be able to transfer into another group later too.
7. Not being opportunistic.
A lot of people get too comfortable in their jobs and don't keep their options open. Even if you love your job, there might be a better position for you with more money and meaning. If you shut yourself off and remain complacent, you won't grow and other people will pass you.
8. Not learning from your mistakes.
Mistakes can be extremely valuable, but only if you learn from them. If you brush them off, then you may keep making the same mistakes over and over again. The more you can improve yourself, by learning from your mistakes, the more you can show your leadership potential.
As Bruce Lee wrote, “Mistakes are always forgivable if one dares to admit them — Don’t be too hard on yourself, learn to accept your flaws and move on.”