I've done my research on collaborations. They often times do not work out unless it's the artist who is reaching out to a writer.If you are in fact a writer looking for an artist, you should have some knowledge of art yourself so that you can make it as easy as possible for the artist.
Take for instance the writer for Death Note (and Bakuman), Tsugumi Ohba. While he isn't all that great an artist himself, if you look at what he gave to the artist, Takeshi Obata, he mapped out the storyboards himself and drew where the characters would be, the dialogue, just about everything but the actual art. Which to an artist, makes the job so much easier.
So if you are a writer, here's what you should have:
An almost a complete story -
Basically, you should have your concepts, ideas, and story all set up before asking for someone to draw it for you. You need a fully-realized story already done, with only the art left to be done. Of course, you need to be flexible for the artist if they don't like where the story is going or something, which leads me into the next point.
Flexibility and teamwork -
If you somehow got an artist working for you, you need to work with their terms. If they don't like something you wrote or if they want something to change with the presentation, or really anything, you have to be willing to compromise. For once you let an artist draw your story, it's no longer just your story. It's both the artist and the writer's. So you cannot hold the artist's ideas or thoughts for granted just because your story is your creation. If you cannot compromise, draw it yourself.
Knowledge of comics -
Much like how the Death Note Duo worked, both had a lot of knowledge of how a comic should be made. As a writer, you should have the skills on how to write a script, or even draw a bit of storyboard. There is a large difference in writing a book and writing scripts for comics. If you just thought, "I have an idea that would work great as a manga! I should hire an artist!" you may need a bit more on your side.
Willingness to do SOME art -
A part of teamwork is the willingness to provide any help necessary for the artist. Things like applying screentones (if you're working traditionally), filling out flats or colors (if you're savvy), or willing to learn a bit to lessen the load (like inking backgrounds or filling in darks) can lift loads of burden for the artist. So maybe have some experience in artwork?
Communication -
This has to be the biggest thing out of everything. When it comes to team projects or even hiring someone, you need to be good at communicating what needs to be done. From costs, to writing issues, to just brainstorming, you need to be in contact with your artist to see what they need, if they're good on a project or if they just need some more time, everything needs to be open for both sides.
Pay -
That's between you and the artist, but know that the artist is working for you and art ain't easy. Most people can write pages of fantasy or make up an idea, but not everyone can apply this to paper as a comic. It's quite hard. So you need to set the right payment for the right content.
So the basic thing is that if you absolutely need an artist, you need to be as easy to work with as possible. Have a fully-realized idea, be ready to compromise, and communicate. Without good teamwork, nothing will get done.
