If you think you are going to sit down at the computer and tap out a perfect novel from start to finish, you are setting yourself up for failure.
Don't let the idea of perfectionism keep you from writing what's on your heart—that is what the delete key is for.
Take advantage of being able to save many different documents under many different folders. Don’t be afraid to write in chunks of little bits of ideas, or move something that isn’t working in a piece to a ‘Bits and Pieces’ folder so you don’t have to let it go entirely, just store it in a ‘closet’ to pull out later when you find a more suitable place.
What you write today is not what is going to be published immediately. In fact, the reason traditional publishing takes so long is that it goes through countless levels of revisions: Your own gazillion revisions, revisions that come from your weekly critique group’s suggestions, Beta readers, an editing service, the agent who falls in love with your work, and finally the publisher, who will direct edits of your work for the bazillionth time (that’s what comes after gazillion, right?).
But don’t let this information overwhelm you, it is meant to encourage you. Why? Because you have tons of chances to get it right.
And if that doesn’t convince you, look at all the people in history who have messed up, but still hold a place in society: Martha Stewart, Bill Clinton, OJ Simson. Okay, the last two were chosen on purpose, to show hard-core examples where people tend to be forgiving and accepting of flaws. As far as I know, no angry pitch-fork wielding mob has come after any of them and stabbed them to death.
Those of us recovering perfectionists (such as yours truly) need to have these gruesome examples to remind us that we are nowhere near that level of scrutiny (except in our own minds) and we are so much better than we give ourselves credit for if we can just put aside our own critical voice and free ourselves to what possibilities can emerge from our fingertips if only we give ourselves permission to be human. This includes letting mistakes, and good and bad ideas flow onto the page without the worry of who will see it, if it will be deemed worthy, and if it will be accepted by others.
Don’t worry about any of that. Free your mind, free your fingers and let those thoughts fly. How many wonderfully imperfect sentences can you write? Let if flow, revise later, keep the nuggets of gold, and as for the rest? That is what the delete key is for.