So you want to be a writer? How can you be a good writer? It would be difficult to define a good writer with just one definition.
Writing is an art as well as a science. Writing is an art since it has various styles to it and it is a science as you would use different techniques to write it.
Good writing however has much more to it than just the common techniques used. [It depends on who your target audience is and whether you know your audience well]
The parameters for a good writer depend on the audience who is going to read it.
For instance, the differences between the style content writers use and the style full-time is that the content-writers mostly use first and second person; whereas a writer for a newspaper would use an objective tone (third-person reporting). The language used is also different for different media of communication.
The general yardsticks to determine whether one is a good writer are to check whether his/her article has a good flow, eye-catching content and the language. The sentence structure, grammar, ideas and the form used are some of the other factors that play an important role in determining whether one is a good writer.
However, there is no one way to find out who a good writer is.