If you don't have any experience yet, it would be a great idea to publish a short story as a novel first. Then look for someone to collaborate on making it into a short comic (one shot). And then, having that as an example of your work, ask if someone would like to collaborate on a longer series.
Personally I would never draw even one frame of a story that doesn't have a fully written ending yet, if it was my first time collaborting with a certain person.
(PS. Don't worry that someone will steal your work - it is already published as a novel, so you can always say you were the first one to come up with it - and check the dates of publishing it, if they don't believe you.)