Meysha's advice is good and will probably work as you're comparing the original with the end product. This is especially the best way to correct brightness and contrast issues.
However, having recently rescued a friend from nervous breakdown trying to print photos in the same kind of situation, I have another theory for you to try.
With PS, make sure that the image is using the same colour profile/space as the program. I set all my images to the European RGB (has lots of numbers on the end) profile and make sure that PS is working in that mode. If there is a discrepancy, some colours - notably asian skin tones, come out in lairy orange with strange mis-density which the printer makes a hash of. This often looks like it's lost the ability to render more than 70dpi and makes you wonder if you've bought a dud printer.
Also, I thoroughly recommend turning off the colour management "enhancement" options as I have never found them to improve matters with photographs. Sharpness, Contrast etc. on the printer just seem to make things worse and introduce digital noise on the fine lines.
This anecdotal evidence is based on using PS 8 CS with an HP Photosmart 7100, but will apply to most of the HP ColorSmart range and probably most versions of PS.
Good luck, let me know if I make any kind of sense!
Rob