First drafts don't have to be perfect, they just have to be written.
It is not without meaning and purpose that it is called a ‘first draft’. A first draft captures the abstract story that runs in your mind, and traps it in ink so that it can take a shape that you can re-look at, and it makes sure that the idea doesn’t fade away. It is written only to be rewritten better and made finer. The concept, content, and the rough base without which you cannot have the story is what makes this preliminary version the most important aspect of getting a good story.
When I wrote my first two short novels, I was most successful in completing the process of writing it. Nitpicking and perfecting everything in your writing when you are just writing it for the first time is unnecessary, and often leads to the work remaining incomplete. I have personally experienced that perfecting unnecessarily while writing also breaks the creative flow, and it can actually lead to the loss of a naturally occurring scene that your mind saw in the flow of writing.
When you are actually writing a story, developing your characters on paper for the first time, what is more important is to capture all the various small, interesting details that come in your mind about them and their setting, even if it is not written in your best form. That is exactly what a first draft is for.
Improvisations, changes, and your best skills come in later as you enhance your draft and make those subtle corrections that you want, to your heart’s content. But, your biggest and most important achievement is to get your first draft written.
Have any incomplete writing? Take it out, and just write your heart’s content without looking back on corrections!