1. Respect the craft by studying it when possible and by occasionally reading biographies or memoirs on other writers' experiences.
2. Maintain a journal in which you write whatever you happen to think or feel at least once or twice a week. This is one good way to help develop what publishers call your "individual voice" as a writer.
3. Read and actually explore specific topics to gain some degree of expertise regarding them but also do this outside of your particular comfort zone to stretch your creative imagination and grow even more.
4. Don't pressure yourself too much. Enjoy the experience as much as you can.