Much will depend upon who your target market and for what use ie Magazine or just private sales. You would need a good google rating to get the site near the top of the list and don't forget to watermark your pictures with a copyright sign.
I would also degrade the images and also use a site where you can dissable the right click and save.
The business of selling pictures is very cuthroat and your images will need to be of absolute high quality with good colour rwendition and focusing spot on. Also research your intended market on subject matter. Pricing also will be a point to note.
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