One thing I can add is that usually we like to do a little work with a person before we agree to actually work on a project. Since ENWorld produces Asgard magazine every 2 months (though the current issue is a month late, sorry), the perfect avenue for us to get experience working together would be to pitch an article for Asgard. Then, if things work out well on that article, we can move along toward whatever product you actually want published.
Of course, if some big name like Gary Gygax, Bruce Cordell, or St. Thomas Aquinas (hey, it could happen) wanted to write for us, we'd probably be able to trust that they're proficient writers.