Hi, I'm on a similar journey enjoying a few sales and lots of nice comments!
Ultimately the question is - are you looking for a business model and then go out and shoot pictures to fill it, or do you want to create images and then look for ways to sell them? In many respects some of the worlds best photography comes from a very personal study - a trip, an observation etc that are at the outset not commercial. However at some point when the work is seen it becomes marketable because of the circumstances surrounding it. This may not be until many years later in some cases, take WWII aerial photography images as one example.
However most of us need cash flow now, unless you have a large other income, especially if we are thinking about the requirement to fund replacement cameras, computers etc. In simple terms, I think the best way to sell work would be to become a celebrity, either real or on the web. Folks love to be able to say, You know so and so, look I've got one of his/her pictures! Example, How many leading photographers today are known first because of their art / photo work, or first because you read about them through articles in magazines and / or stumble across their hints and tips sections while looking for ways to become famous photographers!!!! So a tip would be to look very carefully at the strategies employed by them, they will be different to a "start up" strategy.
Lots at a low price, a few at a high price? Think about that, its an area I'm constantly debating with myself. I though lots at low, but I think you really need a massive network for that and all those I have sold have been mid price and framed.
I'm actually living in Canada but have just spent 5 weeks in the UK where I was born. I spoke to a number of galleries about the "credit crunch" and they were saying that in general they have yet to see a slow down in sales, stating that the kind of people that spend several hundred £ + on art work have yet to be dramatically effected by rising costs.
Reference photography, a couple of points they mentioned were quality, must be top of the range in terms of image and production. Somehow different from what most folks can get from their own camera's - so images derived from well executed equipment / capture / PP techniques that require a level of knowledge / artistic eye / equipment beyond most peoples level.
Convenience - When seeing a framed piece, people may imagine it in their home or office, and if they really like it will buy it. For many people the thought of having to take it to a framers etc just kills the idea of a purchase. (all of my photo sales have been of framed pieces) However the option of changing the frame (ie if the photo is for sale in a gallery / frame shop) is also appealing to local collectors.
Size, Big to make an impact, but not too big! (All my prints so far have been made on a B9180, but a bit bigger would be a bonus.
10 x 8 on 11x14 matted prints that you see in boxes at the art fairs are for most people modest sales and almost no profit if selling via a gallery.
Colour / BW / doesn't seem to matter.
Edition - galleries are still in love with photo editions! We all have our own thoughts on that - be honest about your printing plans!
Other ideas, competitions, enter them and learn from them. Be really harsh on your images, can a day out really produce dozens of "sale" pictures?
Niche - Specialist subject matter or techniques / equipment?
Network with local artists, galleries etc. The art world loves opening shows and you'll find a whole cross section there from dealers, buyers, collectors, artists, students. Many will give advice, but don't just rely on one source, few give all the jigsaw pieces away...... at first anyway!
Hope this helps, there are many different strategies from just uploading your images to a online agent who markets, prints, frames and ships to people who do absolutely everything themselves.
Steven