D.P.I. or Dots per Inch is another way of referring to an images resolution
Typically for print you want a D.P.I of 300+ D.P.I
For web creations images are typically set to 72 D.P.I.
To change your images to a high resolution for print
Go to: IMAGE --> IMAGE SIZE--> (Change resolution from to 300 D.P.I)
This will enlarge the appearance of the image to be much larger
(CNTRL -) to zoom out.
Adjusting the levels
Adjusting the LEVELS of black, grey and white in your images is the best way to create balance in your imagery.
Go to: IMAGE --> ADJUST --> LEVELS
Begin with the grey triangle then only SLIGHTLY adjust the black & white
The goal is to create a photograph that is as close to the original image as possible.