chl, welcome to the world of microstock!
I am reading this thread last few days and I see that you are very passionate about all this, which is very good. It's obvious that you have good will to learn, and I guess that's because you really love photography. And when you love to do something, there is a great chance for you to become good in that.
Your photo is over processed, and many of us told you that already. Madelaide provided you with some good links (on the first page of this thread), and I think you should check them. Also, I think it's very important for you to browse through image base of microstock agencies. If you want to take picture of kites against sky, type it in search box of any microstock agency, and take a look at results. Your image should look similar to results you get. When I say similar I don't mean you have to copy someone, but you have to be able to imagine your photo among other photos. For start, I advice you not to experiment with filters (noise reduction, sharpening, over saturation, too much contrast etc.). Try to make photos that look natural and pleasing to the eye. Your photo with kites could look very nice without this halo around kites, and banding on the sky, and without these strong colors. When you learn basics you can start experimenting with filters and other powerful tools. With your passion, it will be very soon I think...
Good luck!