Be disciplined in your writing. What this means is that you have to make time for writing. Write until writing becomes a habit.
Connect with other writers. Two popular mediums are Goodreads and Facebook writing groups. I have found Facebook writing groups to be a good place to connect with other writers and get feed back. Both Facebook and Goodreads provide opportunities for you to get Beta readers for your book
Write, read and rewrite if necessary. To create a good book takes patience and dedication to your work. Revision is your best friend. You will find yourself doing a lot of it. After all you want your book to be a masterpiece that everyone wants to read. Good luck and happy writing.