To give a photo extra punch, try increasing color saturation.
Create a Hue/Saturation adjustment layer
Go to the Layers panel, click the Create new fill or adjustment layer icon, and choose Hue/Saturation. This adds a Hue/Saturation adjustment layer that you can use to adjust color without permanently changing the underlying photo.
Choose Hue/Saturation settings
With the Hue/Saturation adjustment layer selected in the Layers panel, go to the Properties panel to access the controls for this adjustment.
Drag the Saturation slider to the right to make all the colors in the photo more vivid. If that makes some colors look too saturated, drag the Saturation slider back to the left.
Adjust a color range
To limit a Hue/Saturation adjustment to a particular color range, in the Properties panel go to the menu labeled Master and choose a color range, like blues.
Drag the Saturation slider to the right, and only the blues throughout the image become more vivid. Dragging the Lightness or Hue slider now would affect only the blues, too.
Use the Targeted Adjustment tool
A more specific way to saturate a particular range of colors is with the Targeted Adjustment tool.
Click the Targeted Adjustment tool in the Properties panel.
Click on a color in the photo, keep your mouse held down, and drag to the right in the photo. This saturates only a range of colors throughout the photo that is similar to the color on which you clicked.
In the Properties panel, click the Targeted Adjustment tool again to deactivate that tool.
Save your work
Save the image in PSD or TIFF format to retain layers.
Want to change an adjustment?
If you want to change the adjustment at any time, double-click the adjustment icon on the far left of the Hue/Saturation adjustment layer to reopen the Hue/Saturation controls in the Properties panel.