Edward Winkleman has a new book out which should be of interest to galleries and artists alike.
Artist/Blogger Joanne Mattera reviews "How to Start and Run a Commercial Art Gallery" by Edward Winkleman, HERE, and summarizes what artists can learn in chapter 14:
Chapter 14: Artists: Where to Find Them; How to Keep Them
Make a beeline for these 24 pages. Nothing takes the mystery out of the submission process better than learning how a dealer puts a roster together. Here's how Ed found/finds his artists, in order of frequency: "recommendations (including from other dealers), institutional exhibitions, open studios, cold call submissions."
In other words: show, show, show, show and network, network, network. This goes along with what I know of dealers. Their websites may say "No submissions accepted at this time," but they are always looking. As for cold-call submissions, they are, confirms Ed, "the least productive means of finding suitable artists." If you must go this route, do your homework. "Every now and then an unsolicited submission will make your day. Either the artist has done his research and knows his work is a good match for your mission, or fate smiles on you."