I've been researching a lot on stock lately...I'm not very sure about the demand of the two photos you put in the "portraits" section. For portraits without serious studio setup, look at this guy's portfolio. He has a million dollar gear but I think it is possible with any decent DSLR and lens. :)
For shopkeeper, etc images, I have observed that images with clear view of product sells better. Like if someone is selling medicine...the product medicine should be clearly visible even in thumbnail, the person who is selling it is a part of background. The medicine becomes the main subject.
Also, some of your darker photos may do better if you brightened them up a bit. I have found that photos with bright blue, red and green sell best. You can try overexposing most of your photos by +1/3 stops. It really works. :)
I'm waiting to upgrade to a DSLR before I start portraits so I don't have many good photos right now. Good luck with sales! :)
55-250mm standard lenses. Dual tube macro flash and external speedlit...
i sent most of the photos to keywording today after i wrote this blog..did u really take all your photos without a DSLR with a normal point & shoot cam? how can i adjust the over exposing to +1/3 do u use photoshop to adjust the exposure?