I'm still learning what goes into a great photograph. I've been browsing through some amazing shots on this site, and when compared to mine, there is no comparison. I still seem veeeeeeeeeeeeeeeeery amateur.
What is it that sets apart the amateur from the novices like myself?
Is it the make of the camera that takes a spectacular photograph to begin with? Is it the scenery or the subject that you're photographed, how they're posed or how it appears? Or is it tactful and impressive post production skill with certain programs that can take even the most mediocre image and turn it into a breathtaking work of art?
Hoping to have some discussion on this.
A couple of things to understand, the make of the camera has very little, if anything to do with the "quality" of the final image - cameras do not take pictures, people do - and I do not personally believe that you can take a mediocre image and turn it into a breathtaking work of art, maybe you can, I remain to be convinced. (This will generate some heat -

- I'm sure) I think that most of it has to do with composition, and technical skills and knowledge. I also think that it is difficult to compare various types of photography, e.g. landscape and wildlife, with areas such as still images and portraiture. Some of the good photographers that I know, professionals in their own right, are great when it comes to landscape and wildlife, but wouldn't go near a studio. On the other hand, I would be willing to bet that a lot of the good professionals who turn out great stuff in the studio wouldn't venture to start shooting landscapes or sports action imagery - if I'm wrong, I would like to know.
As Trevor1t says, it's art - it's the vision and the process. There is enough material to read on the web to keep you going until you retire and then some, e.g., I just Googled "photography composition" and got over 9 million hits - yikes! As far as post production is concerned, I would agree that a certain amount of the "final" artistry in an image can be derived from using tools like Photoshop, I mean Ansel Adams was probably one of the best, if not the best to date (my opinion), darkroom technicians when it came to black and white photography, but his starting places were great images to begin with and he didn't have Photoshop to help him - have you tried to use Photoshop to duplicate his results - not easy to do, if you have even tried. Have you ever seen any of his portraits, nice, but he was not Yousof Karsh.
The other aspect to this whole question of
what goes into a great photograph, concerns the viewer. The old saying that
Beauty is in the eye of the beholder is so true when it comes to photographic images. You and I may look at the same image and to you it is great and to me it may look like nothing more than a "snapshot". Why - that is one of life's great mysteries.
I shoot mainly landscape, wildlife and some macro stuff - for me, the essence of a good image would start in your head - your initial view of the subject and its surroundings - you "filter" this whole view through your knowledge and experience - and you subconsciously ask yourself a lot of questions, often without even realizing that you are doing so - things like foreground, background, thirds positions, colour composition, dominant elements, lines, negative space, exposure, depth of field...well you get the idea (hopefully). I think part, only part, of what separates an amateur from a novice is experience - knowing what works and what doesn't work (for you) I, for one, know when I have taken a really blah image

, I also think I know when I have taken a good one.
This is only a part of the story I am sure - we haven't even touched on abstract imagery where the artist makes significant use of Photoshop and other tools in producing his final image. Others will have their thoughts on it as well, but these are my initial ideas - my 0.02¢ FWIW.
Cheers,
WesternGuy