The question I see asked most often in writing groups is a variation on “How do I write this?”, “How do I start my story?”, “Will writing it this way work?”, “What’s the best Point of View to use?”
It’s as though writers have a limited stock of words and have to get them right first time.
If you’re stuck on how to start your story, or a specific scene, then write your way into it. Start with “It was a dark and stormy night”, or “Once upon a time”, or “When he got home”. Then write the rest of the scene. Once it’s all down, go back to that opening that caused so much trouble. Chances are, you’ll find your opening, and just have to delete the waffle in front of it.
If you’re not sure how to tackle a particular scene, maybe because you’re uncertain whose POV to use, or what tense to use, or whether to write in 1st person or 3rd, then write it one way and then the other. You’ll gain a deeper understanding of the scene, and a better idea of which works better.
And above all, when you reach that point in your story where you feel everything is rubbish and not worth continuing, remember: that’s the point where you prove yourself a true writer. That’s the point when you plough on anyway, remind yourself why you wanted to write that idea in the first place, and just see where you end up.