The biggest barrier to writing well is the need for perfection. People who write, which is just about all of us during the formal school years, somehow believe their writing must be perfect. They think that good writers are able to complete or finish things. I am here to tell you that no writing piece is ever done in the writer's mind. The only thing that causes a piece to be complete or done is the deadline. You are done when you are out of time. It is no different than a football or basketball game. It's over when the clock runs out. Sometimes you win and sometimes you lose, depending on where you are when you are out of time. As we know from football and basketball, if you amass a greater number of points earlier in the game, you are much more likely to win. The same is true with writing. If you write and write and write long before the deadline, you are much more likely to have something good at the end. This brings me to my second point...
A writer writes. There is really no such thing as a writer's block. It is more of a thinking block due to lack of writing. In the classroom I can often be heard saying, "Stop thinking. Start writing." It is my belief that all of the things we have taught students about the writing process have actually harmed them. Go into most elementary, middle and high school classrooms and you will see teachers and students working with "pre-writing" activities. These might be mind maps, outlines or similar devices. When students are forced into these rather artificial processes, they tend to believe that when they finally start writing, the piece should already be fleshed out in their minds. This is rarely the case. You figure out what you are saying as you are writing. I encourage kids (and adults) to forego these pre-writing acts and instead just write. So when I teach writing, I ask students to write and write and write for a specified period of time. After they do a kind of mind dump onto the page they can go back and organize and consider ways to improve.
It is important for every writer to use the tools that will encourage the greatest flow in their brains. For some people this is a computer; for others it is a combination of drawing and handwriting. These more artistic writers tend to do better on large surfaces like white boards or chart paper with markers. Writing is about flow. You have to find the medium that best allows thoughts to flow from your brain to the page. Teachers need to assist students in finding the very best tools and allow them to use those tools. I just cringe when I hear that a student is told she must write by hand instead of by using a computer. The writer needs to use what works best for her.
Writing should not be a solitary pursuit. There is no way you can know if you have communicated well unless someone reads what you write. In the classroom this means that students should read each other's work and offer constructive feedback. The very best writing comes from lots of feedback and rewriting. Be brave and let others read your work. It will make you a better writer.
So, if you are trying to become a better writer, get to it. Write and write and write some more, until the clock runs out...