Another approach is to toy with an opening you'd never write, and then make a variation or two. Keep it all or the best of it, and then move on. You might write a dull opening just to get you going. You'll come back to it. Or, you might start at the end, type a little of the middle, and then go to the start or any variation thereof.
Some people like to make an outline so they know what they want to write about.
Knowing that can lead to a start, brilliant or not. The point is and I've said this before writing is rewriting . Of course not. Of course not. All of the arts are about making adjustments, about trying things and discarding some.