I opened this photo of mine, in Photoshop. i then went to image/adjustments/levels. In levels, you have a choice to use the white dropper or black, i used the black as it was easier to identify the darkest part in the photo, which is her heels. that made it level and more accurate in use of colours and lighting.
i also added a personal touch by adjusting the saturation by 7, and contrast by 9; these are found in image (the same way as levels)