I think that if you are focusing on fine art collectors specifically & web-based approaches to marketing the work you'll limit your potential audience & ultimately limit getting your work onto peoples walls and into collections. Do everything you can to get the work up in public places, whether that be galleries, pubs & cafes that show art & photography, etc.
Here in Seattle, a number of artists and photographers bypass the gallery circuit entirely and rent available commercial space for anywhere from two weeks to a month to hang their work. A couple friends make their primary livelihood this way. In this economic recession, there's a lot of empty spaces in prime locations and building owners and relators are quite happy to have a space occupied.
Although the cafe/pub route doesn't seem like a likely place to sell art of any kind, I can speak from my experience. I had not been showing my work for over 5 years (a choice) and to get back into the swing of showing again decided to show in a local pub that hangs art for 2 months per show. 50% of the pieces in the show sold which surprised me greatly. So again, it may not seem the most likely place to show your work, it exposes your work to a lot of people who would not otherwise see it.
As far as online marketing is concerned, I don't see it as terribly effective by itself (although supported by exhibits & being published it has more potential) and would be curious to hear from others who may have had success with it (?).
Getting it in front of people and not on computer screens is really important! Good luck getting the work out !
