You probably know that it's important to be professional if you want to have a successful career, but what does that actually mean? After all, professionalism is rarely taught; you're supposed to pick it up on your own through a combination of observation and osmosis, but that's not always easy to do. And learning on the job can be fraught with land mines, since you might not even see your mistakes coming.

So without further adieu, here are 10 key elements of professionalism that you should master early in your career.

1. Pay attention to the cultural norms in your organization, and follow them. If you watch how others in your office operate, you'll learn all sorts of important things about "how we do things here." For instance, you might observe that everyone shows up precisely on time for meetings, that they modulate their voices when others are on the phone, and that people rely on email for non-urgent questions. These are important signals for what will be expected of your own behavior - and you'll come across as tone-deaf if you ignore them.

2. Be pleasant and polite to people, even if you don't like them. You will have to work with people whom you just don't care for, and even with people who aren't very nice. You'll look far more professional if you don't let them get under your skin and instead remain cordial and easy to work with.

3. Take work seriously. If you make a mistake or something doesn't go well, don't brush it off or use cavalier responses like "my bad." Accept responsibility for your part in what went wrong. Part of taking work seriously leads to...

4. Speak up when work isn't getting done on time or when there are problems with a project. Part of taking real ownership for you work means that you're responsible for alerting your boss when things are going off course, rather than trying to ignore it or just hoping that no one notices.

5. Realize that getting feedback on your work - even critical feedback - is part of the job; it's not personal. Getting angry or defensive or otherwise taking it personally when your manager gives you feedback can be an easy trap to fall into, but it will make you look less professional. And after all, if you care about doing your job well and advancing, don't you want to know where you need to do better?

6. You need to write clearly and professionally. That means no text speak, and correct punctuation and capitalization. This doesn't mean that you need to write as if you were addressing the Queen of England, but you do need to take care that you don't sound like you're texting a friend from a nightclub either.

7. Be flexible. Yes, your workday might formally end at 5 p.m., but if staying an hour late will ensure the newsletter goes to the printer on time, you should do it unless that's truly impossible. That doesn't mean to ignore important commitments in your own life, but you shouldn't let important work go undone just because of your quitting time. Similarly, be flexible when it comes to changes in work plans, goals or other things that might evolve as work moves forward.

8. Show up reliably. Unless you have pre-scheduled vacation time or you're truly ill, you should be at work when they're expecting you to be there. It's not OK to call in sick because you're hung over, or because you stayed up late last night watching soccer, or because you just don't feel like coming in.

9. Be helpful, and do more than solely what's in your job description. The way that you gain a great professional reputation - which will give you options that you can use to earn more money, get out of bad situations and not have to take the first job that comes along - is by doing more than the bare minimum required. That means always looking for ways to do your job better, helping out colleagues when you can, and not balking at new projects.

10. Don't treat your manager as your adversary. If you have even a semi-decent manager, she wants to see you do well and isn't your enemy. But if you instead see her as someone whose job is to enforce rules, spoil your fun and make you do things you don't want to do, it will show - and it won't look good. Treat your manager as a team-mate, one who has authority over you, yes, but one who's working toward the same goals as you are. (And if you're not sure whether this is true of your manager, that's a big red flag to pay attention to.)