Read books on improving writing skills and other works by other authors. Most talented writers were also avid readers. Reading helps expand vocabulary, gives an insight into other styles and techniques of writing and also helps develop creativity.
Sign up for courses and seminars to develop their skills. You will not only learn something new, but also to communicate with other writers.
Carefully follow proofreading and editing, this is very important for the formation of good and correct writing style. It is unlikely that your first draft will be the final version.
Ask for feedback from close friends or colleagues to learn different points of view. Cultivate serenity and use constructive criticism and tips to improve their skills.
Use different sources: dictionaries, thesauri. These are all necessary tools that should be every writer.
Constantly write. Any writer will tell you that the main thing in writing is to write daily, even if you have no mood.