I am still writing my first novel, but this is what I learned in my MFA and from working with coaches:
1) First, just get it out there. Don't worry about mistakes, incongruencies, etc.
2) Revision is what makes a book great, rather than mediocre. Joyce Carol Oates, who has written more than 50 novels, says this. So does Stephen King and most likely, any writer who is worth their weight in gold.
So, just keep writing until the end. You will probably find your story has changed by then, so making revisions before you finish would be a waste of time. Once the 1st draft is done, you can start talking to your characters and asking them what their story is about.
All the best to you,