What makes a good writer?  What makes a successful writer?  What is good writing?  What is success for a writer?  I'm going to look at those questions and give my answers to them.  Your answers can and probably will differ.

What makes a good writer?  What are the characteristics that make one?

1. Enough life experience to have something to say.  A young English major with highly polished sentences and nothing to say is not really a good writer in my opintion.  What's the point of reading well-crafted but empty paragraphs? 
2. Exposure to good writing. To some extent good writing is infectious (as is bad writing), which is why reading good books is a necessity after a session of reading untutored writers.  My grammar and spelling deteriorated noticeably after reading fifty to a hundred First Chapter entries.
3. Some exposure to training in how to write--including a basic knowledge of grammar and spelling.  An extremely powerful storyteller can sometimes get away with not having those basics, but chances are overwhelming that you and I do need them.
4. Creativity--including ability to find fresh ways of looking at the world and at people.   A writer these days is competing with an enormous body of existing literature, much of it out of copyright and freely available online.  A writer needs to say something that hasn't already been said, or say it in a way it hasn't already been said. 
5. Self-discipline. Good writing takes a lot of revisions, getting the details right.  After I finish a rough draft I sometimes look at sections of a story and try to cut the word count by 25%.  I can usually do it without losing information that I really needed in the story.  That kind of tightening can a make a major difference in how readable a story is.   I also try to go back through scenes and walk through them from the point of view of the major characters.  What are they seeing?  What are they thinking?  How can I convery those thing to the reader without stopping the action?  Are character actions consistent with what the rest of the book reveals about them?  That takes time, but each runthrough hopeful gets the story closer to a professional level.
6. Ability to take the useful parts of critiques and incorporate them into stories.  You will miss things, no matter how good you are.  All writers, including Big Name Authors, need editing.  You can sometimes see that when an author becomes very popular.  Several otherwise good science fiction authors have written bloated books filled with unneeded subplots and digressions at the height of their popularity, simply because the publisher knew the book would sell no matter what, and didn't impose the needed edits on the author.  

What makes a successful writer? You don't necessarily have to have any of those six characteristic of a good writer to become a successful writer.  Before I talk about what it takes to be a successful writer, I should specify that I'm initially talking about commercial success here.  I'll talk about other kinds of success later. 

To be a commercially successful writer you need:

1. Willingness and ability to self-promote, 
2. Ability to network and figure out mutually beneficial arrangements with people in a position to help you in your career.  Playing life as a zero sum game usually won't work, at least not early in a career.
   
3. Some kind of trademark characteristic that makes you stand out from the crowd,
4. Ability to create and nourish a fan base.  That can be hard work, but it needs doing, especially early in a career.
5. Ability to figure out where an audience wants to go before they do and before anyone else does, then write something that takes them there.
6. Brashness--willingness to ask people to do things that most people would not ask them to do, and
   
7. Ability to avoid making enemies.  Early in a career a few enemies can do a lot of damage to a writer.
   

I hope I'm not sounding too cynical here. It is possible to be a good writer and a successful writer. However, a lot of good writers will never be commercially successful writers because they lack most of those seven characteristics. Mediocre writers can be commercially successful because they have most or all of those seven characteristics.

Do you have to be commercially successful to be a successful writer or a good writer?  No.  One of my uncles illustrate that point. He was a reasonably successful newspaper columnist at one point, with articles appearing regularly in over a hundred newspapers.  He retired and is now writing books on the histories of various rural counties.  None of those books will have an audience of more than a couple of hundred, and I'm sure he loses money on each one.  On the other hand, he can afford to lose the money.  He loves the research, and loves sharing it.  He's happy.  He is a successful writer.

Labors of love can be successful writing and even good writing, even if they have no viable market whatsoever.  I'm a major history buff, and about ten years ago I started researching what I intended to be the background for a story set in an alternate 1946 where World War II was still raging.  I ended up writing over a hundred pages worth of background material but then abandoning the actual story.  I put the background on my website and gained nothing from it financially.  Was that a bad use of my time?  Maybe, but I enjoyed it a great deal, and still consider the results to be among the best writing I've done--though fair warning, the web design work looks awful.

Success in writing can be getting a novel published by a major publisher.  It can also be getting a few dozen copies of the story of your life printed off so you can give them to your grandkids.  Maybe you read my description of what makes a successful writer and said, "Yuck.  I don't want to be that type of person."  If so, that's no reason to give up on writing.  If you enjoy writing, write.  Write for yourself.  Writer for your friends.  Just don't expect today's world to come knocking on your door, no matter how good of a writer you become. 

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