what do comic writers and editors typically look for in an art portfolio?

A lot of people bring half-finished art in their portfolio. Don’t. It’s better to leave that stuff at home. And don’t bring work you have progressed beyond ‘to show improvement.’ Leave that at home, too.

There are a lot of cover artists out there. IF you only want to do covers, you aren’t competing with the worst out there, but the BEST. So if you are doing single cover-like pieces, better be able to compete with Adam Hughes and Artgerm, OR bring something entirely new.

What they do need is sequentials. Get a proper script and draw the best pages. Use creativity and storytelling basics. WOW them.

That’s it!