MicrostockGroup

I hope you're not planning on just submitting to iStock or even become exclusive at some point...?

iStock tends to be one of the pickiest agencies out there. It's quite easy to feel inferior when submitting to them (up to the point when you understand what they are looking for...).

The images you applied with may not even be approved afterwards, due to technical issues that were not apparent in the smaller file size versions. So that's no surprise. Happened to many of us.

You have to get comfortable with the iStock standards in terms of technical quality and concept. Then it will be better.

Like I said, sign up with other agencies as well like SS, FT, DT etc. (you see them on the right here -> )and upload all your stuff there as well.
Not only will it give you more self confidence but also a few more bucks in your wallet 

Good luck!

I would not take Flickr comments as any sort of useful critique.  For example:
http://www.flickr.com/photos/flixel/5387686007/#
"Such a beautiful picture! Fantastic!"
In the context of micro, it is over filtered, the white balance is off, you have blown highlights, and you've clipped the corner and shadow.

http://www.flickr.com/photos/flixel/5390677717/#
"clear, simple and beautiful "
For micro, it is an underexposed, oversaturated subject with far too much white space.

http://www.flickr.com/photos/flixel/5325141448/#in/set-72157625569214195/
"Looks good enough to eat..great image."
Multiple lighting sources, poor white balance, over sharpened, over saturated subject.

These are all simple subjects, and as gostwyck said, you should be able to nail them, because the 500,000 contributors (or at least some subset) before you can nail them, technically and artistically.

So true, Flickr is an oversized photo club where people judge the "beauty" of images, which has little to do with the salability of images for stock. Not that you can't have a beautiful stock image, on the contrary, it's just not the only criterium.

To a point.  The things you want to do to them is get the levels right so they appear properly exposed. 

Also, if you are going to submit anything "over white", it had better actually be white.  The dull gray is unlikely to be accepted and even less likely to sell.  Try exposing a lot more to the right when you shoot something isolated, and use the dodge tool to get rid of any stray gray areas. 

I wouldn't of started with istock for 15% commission, when they don't sell new images well and they have so many premium collections that they are trying to push.  They can also cut commissions again, I just don't see an incentive to build a portfolio from scratch any more.  Shutterstock is much better but they're hard to get in to now.