Are you unknowingly ruining your career? Check and see if you're making these simple mistakes that may be leading to your self destruction.

When you're writing a letter or an email it's important to check your spelling and grammar. I know a lot of people just cringe at grammar and spelling mistakes. Not using capital letters when you should, writing the word "a lot" as "alot", not knowing the difference between "to" and "too", or the difference between "your" and "you're" can really make you look stupid or careless. I see it all the time and it's not just college kids making the mistakes. It's grown adults who should know better. Even if it's just a short email, it's important to use correct spelling and grammar. If you don't know the difference, look it up or ask.

It's easy to say, "Yeah. I can do that." Or "Sure! No problem!" The problem is that it is a problem and you can't do it. Sometimes we over promise. It just means that you're optimistic about your skills and time management; which isn't a terrible thing. You just need to know when to say no, otherwise people are going to think you're a flake which is a terrible thing. If you do it one time, nobody will think anything of it. They may be a tad frustrated, but if it keeps happening, it could spell bad news for you because you look like you can't be trusted with things.

Everyone talks smack. It's just a fact of life, but if you talk smack behind someone's back, that's not OK. Talking smack with the guys at the office about how their football team is terrible, or their girlfriend is too pretty for them or something along those lines is OK, but making personal attacks about their character or work performance is off limits. So is gossiping. You look like a Negative Nancy. People may also think that you're jealous of something. Coworkers may also wonder if you talk about them behind their backs. It's even worse if you do it around your boss.

Making mistakes happens. No one is perfect and a mistake is going to be made every once in a blue moon. When it happens, own up to it and say something. Not owning up to a mistake and trying to place blame on someone else or making excuses makes you look incompetent.