Caps Lock switches your cursor to Plus sign for precision, while working with painting or editing tools.
To draw a straight line, click where you want the line to start, then go to the point where you want the line to end, hold Shift and Click.
Holding Ctrl will change you current tool to Move Tool, temporarily.
Holding Spacebar will change you current tool to Hand Tool, temporarily.
Holding Alt will change you current tool to Eyedropper Tool, temporarily if you are working with a painting tool.
Ctrl + Alt + Click and drag the image, it will create a duplication of the current image image or selection and make an overlay on top.
If you hold down Alt while using Burn or Dodge Tool, it switches the tool functions in between them.
When you are done typing with any text tool, press Ctrl+Enter, Photoshop will understand you are done.
Alt + Mouse Scroll changes the zoom level
While using Magnetic Lasso Tool, pressing Delete button will remove the previous anchor point.
While working with Zoom Tool, Ctrl + Spacebar = zooms in, Alt + Spacebar = zooms out.
Eyedropper Tool to captures foreground color, hold Alt and click, it will capture the color for background.
When drawing a line with Measure Tool, if you hold Alt and draw another line from the end of the first line, it will also measure the angle.
When using Marquee Tools, hold down Alt and it will make the click point as the center point of the selection.When using Brush Tool, or other Paint Tools, pressing the numbers on the numeral pad will alter the transparency. ([4=40%] or [press 4 then 5 will get 45%])
Hold Shift and press "+" or "-" it will change the layer and painting modes:
N = Normal
I = Dissolve
M = Multiply
S = Screen
O = Overlay
F = Soft Light
H = Hard Light
D = Color Dodge
B = Color Burn
K = Darken
G = Lighten
E = Difference
X = Exclusion
U = Hue
T = Saturation
C = Color
Y = Luminosity
Q = Behind 1
L = Threshold 2
R = Clear 3
W = Shadow 4
V = Midtones 4
Z = Highlights 4
(This will work with these tools: Alpha turned off, Indexed Mode, Line tool, Bucket Tools, Dodge and Burn)
Double clicking on the title of any panel will minimize or maximize it.
All "Cancel" buttons in every Photoshop windows and tables, will be transformed into a "Reset" button by just holding Alt.
Pressing Tab will hide toolbar and panels, while Shift + Tab will only hide panels. This is one the most used trick in Photoshop.
Let's have some fun, wanna change the grey background color outside the opened file, select Paint Bucket tool, hold shift and click. Voila! (works only when a file is opened)
Open a file and press F button, it switches among the 3 different screen modes so you can easily choose the best workspace for your current task.
Ctrl + Backspace and Alt + Backspace will fill in the whole image area with foreground color or background colors.
Pressing Shift + Backspace will pop-up the option window, Alt + Shift + Backspace and Ctrl + Shift + Backspace, will fill the image with foreground or background color but will not change the values in of the areas of alpha.
Ctrl+J makes a duplicate layer.
Ctrl + D to deselect everything, and Ctrl+Shift+D to reselect what you deselected.
You can show or hide a path by pressing Ctrl+shift+H
Pressing Ctrl+Tab allows you to toggles between opened image files.
Alt drag a step from a serial action can copy it to another action.
If you want to import an object from Illustrator to Photoshop, just Copy and Paste. Photoshop will ask you whether to import it as a vector or bitmap.
Double clicking the Hand Tool will provide you the largest full image preview possible.
Double clicking the Zoom Tool sets the zoom level to 100%.
Pressing X will swap the foreground and background colors.
Pressing D will resets the foreground and background colors to default (mostly Black and White)
Ctrl+Shift+N opens the new layer with a dialog box, Ctrl+Shift+Alt+N creates a new layer, no questions asked.