greeting cards: tough market. Lots of footwork on your own. Have heard of big
company rip offs of little folk (Polis some years back one example) who manage
to do everything right and make a moderate splash. If you're serious, all good
luck to you.  Maybe best markets for do it yourselfers (who are very good) are
museums, specialty shops. Profits: somewhat like groceries, or so I've heard.
Publishers pay flat fee, but negotiable according to reputation, portfolio.
Write to them for guidelines and months for submissions.