You always hear different opinions on this one and it's no wonder, as you meet a lot of people with different view, different aims and different achievements, but all of those opinions that are worth paying attention to usually include this:
Flexibility - be comfortable with the ever-changing technology and do not be afraid to be a step behind. You way better of trying to master yesterday's technology, than misusing the equipment of tomorrow.
Vision - develop your sense of composition. The overall composition, the proportions of layout, denotes importance of the elements. Only you can decide which features appeals to you, and how best to emphasize them. This means knowing when a scene is lacking something and also when it's way too busy. You might end up in situations when enough is too much sometimes, thus knowing what to exclude is just as importing as knowing what to include. Anything that isn't a part of the subject or its context is only a distraction, cluttering up the image and diluting the message. What you have to do is eliminate extraneous surroundings - usually by moving closer to the subject - and make a clear, tidy shot. Painters create art by addition - adding more paint - whereas a photographer creates art by subtraction - removing unnecessary elements.
Sensitivity - Learn to recognize the subtleties of colour, texture, and lighting.
We first notice the subject's colour or tone - calming blue, natural green, foreboding black. Then we see shape: soft curves, hard edges, sweeping lines. You, as a photographer, can manipulate this by searching for shades and shadows, shifting intensities of tone and hues. Skilled photographers develop a "light style", learning to recognize a particular type or quality of light that they prefer - and then exploiting it to the full. This is a highly refined sensitivity to light quality that only a few fortunate photographers ever achieve. Experiment, because developing a comprehension of and sensitivity to light in all its forms requires an investment of substantial time and effort, but understanding light is without question the most difficult aspect of photography - and the most important.
Learn from your mistakes and don't be too proud to look at them critically. Be interested in what you're doing, get used to follow the photography news and filter them in a way to adapt the technology for your own needs.
The qualities of a good photographer are many, but the most important thing is to possess an ability to put your object of photography on a level of comfort both with yourself and with the ambience. This is the most important criterion for a good photograph. A good photographer should be creative and also be willing to explore the potentialities of his subject. The most important message to convey is not just the subject of the photograph but the feelings that can be received from it. This means you not only have to show what the camera snapped, but also try and reveal what you saw in your heart.