Most top writers believe in the philosophy that writing every day is essential for success. However, who has the time to create parts of a story from a blank page or screen every single day? Anyone who is disciplined enough to take the time for it. Sitting down and concentrating must be a priority. Does this mean creating 5 new pages every single day? No. It means doing what you can with the time you have. All of us have 15 or 20 minutes to devote to creativity. Turn off the TV, get off social media, put the phone down. Whatever distraction is in the way, move it aside. Jot down some notes. Edit something you wrote yesterday - it's probably not perfect. Expand on it. Polish it. Make it better. Once you get in the habit of writing something every day, you can write longer every day. It's like learning to play a musical instrument. Once you develop the muscles required for the basics, you can go on to more advanced exercises.
Once you find your writing voice everything else will be a little easier. You will know how you want to phrase something. You will develop a following. Your fans will expect a certain level of excellence, and you will be able to deliver. Editors and agents will love you - or at least like you. They sure won't hate you. You'll be somebody they can depend on.
Discipline is another key that should be on the same ring as priority. Don't waste the time you've set aside for writing. Utilize it to its fullest. Get a lot accomplished. Don't lose those keys. Hang to them. They open a lot of doors.