1. Write a little bit every day. Get a journal or something and just write. It doesn't have to relate to a story, it can really just be about your day, but get into the rhythm of writing and letting words flow at least once a day.
2. Read. A lot. If you want to be a writer, you have to be familiar with the language and how others are using it. Also, reading can give you inspiration.
3. Write through your writer's block. As I read on John Green's website, you never heard of a coal miner getting coal miners block. Just keep writing and push through it.
4. Know when to stop writing. I know this goes totally against what I just said, but if you are about to get to a really intense part of your story, stop. This will give you time to think about exactly how you want it to go, and it will also prevent you from having writer's block the next day and will make you excited to write.
5. Know your characters. If someone asked you a totally obscure question about your main character, like what their favorite band would be, you should be able to answer it. Even if it isn't anywhere in your story. As author Barry Lancet said in an interview, "I often have arguments with my main character about who knows more Japanese culture." Have that relationship with your characters and your readers will connect with them too.