I feel like I'm full of writing adages as of late. Hopefully they're more helpful to you than not.
Tip to all writers: Write until you can't.
I know that sounds obvious, but let me explain. Sometimes what you write is crap.
That doesn't mean you stop. Think of it as a halfway decent box of chocolates that doesn't have the types labeled. Sometimes, you have to work your way through some bad pieces to get to the stuff you really want. Writing everything is like clearing the filter in your brain -- clear out the noise, then concentrate on the story. Write it all down, don't pause, don't quit, just worry about the junk later. Ask my students (adult or teen) later about how I will make them write without allowing them to go back and do any editing. The point is to get what's in your head down on paper/screen before you lose your train of thought and end up getting up to get coffee... brb...
Kidding. You must clear the way for the good stuff that's rattling around in there waiting to be part of your story, but your brain sometimes needs to warm up. To do that, you have to just keep typing/writing away.
In a way, this blog is my way of clearing the rest out. Even though I'm editing, I sometimes need to get the rest of my thoughts out so I can concentrate on what I'm writing. Editing does not mean that there is nothing new to the story. In fact, sometimes this is where elements of the story really pick up because you, the writer, see points in the story where you can enhance aspects of your character or build back-story, or describe that event that you didn't have as much time with on the first run. Like I said, write it down and don't stop. Editing is when you can fix and add what you need to.
I'm not saying to avoid describing setting/conflict/back-story by doing this. If it is in your head when you're writing the first draft (or fiftieth), put it in there as you see it in your head. I am saying that, even if you don't see it on the first draft, you know there are parts that need backstory or more description. It will be there when you return. If you're really afraid you're going to miss something, leave a proofing mark to come back and flesh something out. Honestly, though, if it is in your head and nagging at you, it will come out one way or another. Just don't stop. Write until steam comes out of your ears and your hot coffee has become the temperature of iced coffee or you're picking up to sip from an empty cup 2-3 times. Write until you can't and then, when you do stop, think about what you've written to make sure there isn't more. Then write more and more and more.
Whatever you do: Just. Don't. Stop.