It will take time and patience which may or may not be rewarded. If you have a sheltered area right next to your door, set out a box or bed for the cat placing inside it a piece of material that has your odor on it. Place the food next to the bed. Quietly sit down a little distance from the food. Eventually the cat will get used to your presence. Gradually move the food and the bed closer to your door. You can then move them just inside the door . If she decides to come inside, don't close the door suddenly so she won't feel trapped. In time, she may get accustomed to the idea of coming indoors. Don't rush to pet her as touching may frighten her. Depending on the age of the cat and whether she is feral or a stray, this will take time.