This might be a really stupid question, but I wasn’t able to glean anything useful from a search (thanks to the auto-zombified threads that have been turning up).
Anyways, I was wondering what kind of contact process one goes through if you’re interested in doing illustrations for books or book covers. Is this usually a process where the writer gets together with an artist, and they submit everything together? Or is it something whereby the publisher or agent looks for an artist once they’ve decided to go with the manuscript? In other words, if I wanted to look into doing book cover illustrations, should I be seeking authors,agents, or publishers?

But the thought’s appreciated nonetheless. 