Well, it depends on where you happen to be in your career.
Assistant Editor is the entry-level position at most companies. But these days, the competition for the relatively few jobs even at that level that open up is fierce,
So getting any experience that you can in the world of storytelling and project management is going to be a plus. It need not even specifically be comic book editing–working in theater, or in prose, or in media and so forth can also have an application to what we do. Ultimately, we can train somebody in the nuts-and-bolts of what an editor does, but it’s much harder to train them to have good storytelling instincts. Those tend to come with experience.
At a higher level, you need to have a lot of experience in a related field. We’re not going to bring somebody on board at the Editor level unless their qualifications are so strong that they are a more viable and appropriate candidate for the position than anybody who is already a part of our team who might be in a position to be promoted up.
After that, it comes down to the same three elements involved in getting any gig in this field: talent, perseverance and luck.