@onigiriinu A few questions for clarification's sake:
"I won't be paying unless we are getting a promotion or something"
What kind of promotion are you referring to? People unfamiliar with Webtoons might want to know.
You might want to state how much say you - as an artist - can have in the story, and how much say the writer can have in your art. Also, do you need thumbnails for your panels(I'd assume so)? How much direction is "too much"?
These are the kinds of things that usually go wrong in collabs, so I wanted to make sure that you and your collaborator discuss things out FIRST, before going forward with the big project. Also, doing something small first could help to see if you guys work well together. If you start off badly, it's only going to devolve from there. A strong management of self and the collaboration is needed.
Finally, which one of you will have the final say in creative decisions? Is it the artist? The writer? Or will the writer have final say in all things that have to do with writing, and the artist with all things art? WIll you two be able to compromise on your individual visions just a little bit to make sure that you both can retain the excitement of creating a webcomic together?
I've offered my few pieces of insight. I hope this will be of help to you guys when you start your collab. Also, be sure to discuss who owns the right to the final comic strips(which contain BOTH writing and art). Will you both have the files on your computers? Who decides on where you post them online? Is mutual agreement needed?
Anyway, just don't start your collab with just anyone, no matter how skilled they are. Same goes for the writer. Chemistry - how well you two work together - is very important in collaborations.
A few conceited trips for writers(please bear with me): Even if you miss your chance of nailing a collaborator today, don't despair. Go back to writing, work on your storytelling skills(especially script-writing, panelling and plotting if you want to work on webcomics) while keeping watch for any artists requesting collaboration. And I recommend being active as well, learning to pitch yourself professionally and having a set of writing skills that you feel confident in. Here's two other sites where you can seek for artists:
The subreddit people require you to act professional, even if you aren't one yet. Be sure to read their rules and find good references to excellent pitches online. Remember - you don't EVER need to convince them of your ideas - you need to convince they should collab with you.
For more ideas, visit https://forums.tapas.io/t/thoughts-on-collaboration-writers-looking-for-artists-kind-of-posts-and-vice-versa/10106/6 to hear artists' view on things, and what attracts them to a writer. And remember - collaborations aren't collaborations until both sides of the collaboration can have say in art and writing. The partnership needs to be equal.
Alright. I'm out. XD