1. Be original.
2. Don't use the same lame plots 90% of vampire novels have (romance).
3. Make your characters people who have LIVES and act like people.
4. Have a better plot than 'romance'. Have a secondary plot in it as well, that twines together with the main one.
5. Learn writing skills - how to do characters without describing the laundry list of how tall they are, what color their hair is, what they wear, how long are their eyelashes, ad nauseum. Good writers don't DO that crud. Learn how to pace a story. How to build to a high point and how to bring the story to an end.
6. Understand that by no means is your first draft anything other than drek. Writers rewrite their work five to 10 times, to get a publication worthy manuscript. It's a starting point, most of what you wrote will be thrown out as you fine tune it.