As a writer who has worked with multiple artists for my comic, I'll tell you my secret: Paying them for their time and labor. Up front.
Doing the art for a comic page takes significantly more time than writing it. On a scale of oh, 8 hours of art to oh, 8 minutes of writing, on average, for me. My artists invest MUCH more time per page than I, in something that is more labor intensive and has more years of effort behind it. They deserve to be compensate for it fairly.
And fairly is the key term here, and a fair rate will certainly vary between artists. Some might find the promise of hypothetical future revenue to split to be worth the up front investment, but I can't honestly blame any who don't, as they're putting in dozens to hundreds of hours of work for possibly NO financial return.
You're more likely to have success finding a consistent collaborator when at least part of the equation is a per page $$ rate. And while it sounds from your other thread you plan on providing sketches to the artist, I hope you understand that is also the much smaller portion of the labor, especially when it comes to them as scanned handdrawings that they'll likely have to sketch over regardless.
Just my two cents. Good luck.
