Here is a essential shortcut set for photographers using Photoshop to make your processing faster.

Work space:

F  Switch Between Screen Mode

CTRL+0  Fit Image In The Screen or Window

CTRL/CMD +  Zoom In

CTRL/CMD -  Zoom Out

CTRL/CMD+TAB Flip through Open Documents

SPACE = Move Through Image with Hand Tool

Tools:

B  Brush Tool

F5 Open Brush Settings Panel

0 - 9 Set the Opacity of your current tool

SHIFT + 0 - 9 Set the flow of your current tool

X  Switch Between Foreground And Background Color

D  Reset Foreground And Background Colors to Black & White

V  Move Tool

C  Crop Tool

G  Gradient Tool

M  Selection Tool

SHIFT+L  Toggle Lasso Tools

I  Eyedropper Tool

P  Pen Tool

Z  Zoom Tool

S  Clone Stamp Tool

SHIFT+J  Toggle Patch Tool, Spot Healing Brush etc.

SHIFT+O  Toggle Between Dodge & Burne Tools

CTRL/CMD+ALT+ Right Mouse Button  Adjust Brush, Small or Big (Moving mouse to left or right) / Soft or Hard (Moving mouse down or up)

Layers & Saving

CTRL/CMD+I  Invert (Selection and Mask for example)

CTRL/CMD+ALT+I  Image Size Adjustments

CTRL/CMD+ALT+SHIFT+E  Make A Stamp Visible Layer

CTRL+ALT+S  Save As

CTRL+ALT+SHIFT+S  Save For Web

I have added these to the Shortcut Setup ease my work:

CTRL/CMD+ALT+SHIFT+K  Shortcut Setup

CTRL+ALT+SHIFT+M  Add Mask (Layer - Reveal All)

CTRL+ALT+SHIFT+G  Gaussian Blur ( Filter - Gaussian Blur)

CTRL+ALT+SHIFT+U  Unsharp Mask (Filter - Unsharp Mask)

CTRL+ALT+SHIFT+F  Flatten Image (Layer - Flatten Image)