I remember the first time I read the book "Thinner." Stephen King is just this amazing author who knows how to use the English language to creep you out. Truth be told, when I first seriously realized I wanted to become an author, it was because of him. I idolized him and wanted to be just like him.
Not that it wouldn't be fantastic to put out an amazing novel every year and earn the royalties that go along with it (I'm sure that doesn't even factor into it...), in reality, I ddon't pace my stories well and my venacular is lacking. I'll never be an amazing horror author like Mr. King. But I know that, and it saves me a lot of heartache down the road.
All writers, great and unkown, have different weaknesses and when we start off, we don't see them. The truth is, we need someone else to point them out, and even when its done as nicely as possible, its not always nice to hear. Eventually, we learn to accept those weaknesses, and work on them.
The sooner you find your limitations, the sooner you can start working to correct them, or ignore them. (Depending on the situation) If your weakness is grammar, you'll need to refine your skills in language and sentence structure. You may need to work extra hard to avoid cetain words (We all have those words we fall back on, too. Mine are as and that.), or learn comma usage. These take time. And when I say ignore, I don't mean act like it isn't a problem. I mean, if you can't effectively write in a specific genre or subgenre, you should pretend that genre doesn't even exist in your writer mind. (Say your technicalogically challenged, sci-fi may not be for you)
How can you do this, though?
There is no such thing as a perfect writer (take a deep breath)--everyone has to work hard to make their published dreams come true. The best things I can suggest are: working with other people to make your work perfect, take classes on language and composition, and avoid genres you aren't comfortable with, or don't know a lot about.
Also, these things can change over time. The more often I avoid using those words I use as a crutch, the more often I have to search for other words that I use too much. This can happen with your work as a whole, too. The more I write, the better my writing gets. I may have a great middle and ending, but my beginnings are always bad in a lot of ways. They require more attention when editing, which is why I tend to edit a story from end to beginning.