When you’re writing your first draft you’re on a learning curve discovering who your characters are, what the world they inhabit is like, and what’s happening in the story. It’s important to know when you begin that you’re not actually expected to know all these things when you start typing the first line. I’ve seen plenty of checklists floating about that ask ranges of questions designed to make you think about the world and characters but suggest you need this stuff before you start. What they don’t tell you is that you don’t need the list of questions.
Trust yourself, it’s as important as trusting the reader. When you have been reading books or watching TV or films no doubt you’ve sat there and detected when something about a story doesn’t quite jive. You need to trust that you will be able to do this with your own story and that when the moment comes you’ll be able to answer the question naturally within your work without it being explicitly stated. For instance, you don’t need to know when you begin what the main character’s favourite colour is, unless this in something of vital importance to the story. However, as you go along you might notice a colour reappearing, perhaps they wear a lot of red, or they keep painting things yellow or there might be a lot of rainbows about. Alternatively another character might ask them and now you’re further into the story you can answer it, sometimes without thinking.
Similarly with the world they inhabit it sometimes best to let them move about in it to find out what it’s like. If you end up with too much description it doesn’t matter, you can easily trim it during editing, or hack it, depending. Sometimes an emphasis on knowing everything before we start can actually hinder rather than help because it can make us feel like the first draft needs to be perfect. It doesn’t. It’s perfectly acceptable during a first draft to change your mind halfway through or answer the same question differently every time it’s asked, even if you don’t mean to. It doesn’t even matter if the layout or decoration of a reoccurring environment keeps changing until you find the right one.
The thing about first drafts is that they absolutely aren’t perfect, that’s why editing is so important. It’s not the planning or the first draft that really makes a story, it’s the editing.
For more writing advice see my archive page.