The great secret that should not be so secret. It is secret mainly because of corporate sponsorship and the consumer drive to have the biggest, the best, the "greatest". It is manifest in the camera brand wars that we see on the net, at the club and even in the home between family members.
Great images do not come from a great camera in the same way that great carving does not come from the chisel, great cooking does not come the stove and great writing does not come from the keyboard.
Great images come from the eyes, mind and hand of the person that made them.
Better tools can be helpful if they are well known and well understood by the mind using them otherwise the mind-numbing additional plethora of options can simply get in the way of a good photograph.
That vision is more important than the tools is borne out by the selection of timeless images that have come from photographers of the past. They did not have latest sensor X, brand Y and model N-1. They had a box with a simple glass lens in one end and a glass plate covered in emulsion at the other end. The really advanced ones had an adjustable box with a bellows. Ask yourself why these images are still with us today.
So what do you need to create great photographs? Vision. An eye to discover from the people, things and places around you what YOU like to photograph. Thats all it is. Simple. In photography creating the image is all about you. Once your image is viewed it is completed by the viewer. They interpret your vision into their own.
Yes there are the classic rules and it does not hurt to learn them - but don't be driven by them (I'm not going to cover them plenty of others have). Break them when your vision says you should.
Want to discuss this? Look me up on Google+.