When people think of the writing lifestyle, they imagine hours alone, seated at a keyboard, hobbled by a crazed fan. While there may be more than a little truth to this, especially if the writer is a character in a Stephen King novel, the reality is that successful authors don't make it on their own. They need a team of supporters, especially in the early years of their career.
It's difficult to judge one's own strengths and weaknesses in writing. The author is too close, too attached to the words to make a completely accurate self-assessment. Add onto that the difficulty of filtering the readers' expectations and opinions. Bottom line: don't expect to write a best-seller without others' feedback.
While in school, we have teachers who evaluate and help us improve our writing. What critical resources exist beyond graduation?
Don't write in a vacuum. If you intend to publish for a wide audience someday, you need to let a smaller audience help you refine the early, uglier drafts.