You’re a game designer as well as a writer. Before you put finger to keyboard, you should know the design of what you’re writing. And that means knowing what the qualities are, how the content is structured and how the character moves between one storylet and the next.
There’s no need to do everything at once, though. Plan your content in chunks of six or ten or fifteen storylets, and have a plan for how these chunks fit together and which qualities are common across the chunks. If you have ‘resource’ qualities that are built up and then spent, figure out how much each is worth, and whether they can be exchanged. Work out how many actions you want this chunk of content to take up.
Doing this will save a lot of time in the long run. And it will save you having to discard a bunch of great prose that is suddenly useless because the old structure didn’t work and there’s no place for it in the new structure.
A good way to work is to ‘skeleton’ out content before writing. Create all the storylets and branches you’ll need, and set up all the quality requirements and changes. This means you can playtest the structure and make sure it all works before you sit down to write the fiction. Also, if you’re working as part of a team, you might find that you have a good designer and a good writer. There’s no problem with someone designing the structure of content and someone else writing it, if they communicate well.