Fungii wrote:Another question is how do you work with a writer??
Very carefully. We're fragile flowers.

Seriously, though, I'm going to give you a way-too-long answer, because I think starting out on the right foot is the best way to ensure that a project actually works and everyone is happy.
1. Pitch your idea and see who bites - this will give you a baseline group of people who are enthusiastic for your project.
2. Ask for writing samples - this will whittle the group down to the people whose work YOU like.
3. Chat with your top candidates about their ideas for your project, their work habits, and communication style. Even when working with someone else's idea, most writers need a little creative wiggle room, so you want to find someone whose vision matches yours (better yet: someone whose ideas make yours even better), not to mention someone you feel like you can talk to and rely on. I kind of hate the idea of a chain of command in a small team, but like agentyoda said, be upfront about how much creative control the writer will have. Ideally, flexibility on your part is better (for the writer, at least!), but either way make expectations clear. Talking about these things early on should ping any red flags and (hopefully) make one person stand out as a good fit.
4. Once you settle on a writer, start talking specifics: go over your outline or any specific details that are important to you, have them help you flesh out the details that are missing, and start working on the big picture of the project (detailed outlines, character profiles, etc). Also talk about non writing/art responsibilities, like coding and music, and figure out who will handle them if it's just going to be the two of you. Figure out together how and how often you want to communicate: do you want to see new writing scene by scene, once a week, something else? Do they want to see sketches, finished work, have short daily check-ins? Clarity here will save you both a lot of needless misery if you aren't on the same wavelength; don't assume anything. For something like NaNo in particular, it's also important to talk scope: how many words will they realistically be able to write in a month, and what sort of art assets will you be able to give them to work with? If your limit is two sprites and two BGs (or whatever), it's important to know that at the start, because it will definitely shape the story. (Hint: most writers have no concept at all of the amount of time/effort that goes into making art, so shut down any "maybe we could add just one more sprite/pose/outfit/bg/cg" talk as early as possible).
5. Communicate as planned. Exchange work and feedback, fixing problems with writing/art as you go. Ideally, with the right pre-planning, things will go smoothly, but if something isn't working, speak up. It's important not to be overly precious about your work, but a lot of writers struggle with this. Sandwich criticism with compliments, and if there's a major problem, be firm but kind about it. (This is also a reason to be on the lookout for insecurity in stages 1-3: it will only get worse). If you run into any major delays, talk about it. If you're loving the way things are going, talk about it. If you don't have time to talk about it, TALK ABOUT IT. Being afraid to communicate, or putting off communicating, is basically the worst thing you can do for a project. Agreed upon radio silence is fine; biting your tongue and bottling is toxic.
6. Repeat #5 until complete.
7. High five, you made a game!
TL;DR: TALK TO EACH OTHER
Also, bonus tip: writers are going to show up because they love your art, and showing them art will make them SO HAPPY. That crappy sketch you're probably going to redraw? They want to cuddle it. Seriously. Collectively, we writers can barely finger paint, so what you do seems like magic. We hope you feel the same way about what we do, but - LOOK! ART! *Points! Sparkles! Pets!*