Read, read, read. You cannot become a good writer unless you read good writing. Then write, write, write. It's likely your initial efforts will be terrible. That's OK. No one gets it right in the beginning.
The other bit of advice is to master the language. A good idea isn't enough. If you haven't the competence to execute that idea, then you've failed.
In short, if something's worth doing, it's worth doing well. Writing is no different.