Time is free but it’s priceless and when it comes to Photoshop time is one important factor that affects your efficiency and design. Below are some shortcuts that are very useful on the long run and will help. (Note: all shortcuts have been written in reference to Adobe Photoshop CS4). This article was written on windows so for all mac users control=command and alt=option.

1. F7 : open and close the layers palette.
2. CTRL + T : Brings up the transform tool . Pressing SHIFT will keep it proportional and pressing ALT will keep the center intact.
3. CTRL + 0 : Fit Screen
4. CTRL + (+/-) : Zoom
5. [ : Decrease brush size . ] will increase it.
6. Shift  + [ : Decrease brush hardness. Shift + ] will increase it.
7. ALT + SHIFT + O : Overlay Blend Mode (Comes handy…)
8. Ctrl+ Enter : Commit Changes when in text mode .
9. Spacebar : Used to drag a selection . Try it for yourself . Press M for Marquee . Create a selection and press Spacebar with the mouse key pressed.
10. D : Brings up the default background(White) and foreground(Black) color.
11. X : Exchanges background and foreground color
12. Ctrl+J : Duplicate a layer.
13. Ctrl + Delete : Fill layer/selection with background color . Alt+Delete for foreground color.
14. Alt + [ or Alt + ] : Scroll within the layers palette.

These were some keyboard shortcuts that help you a lot.

STILL NOT SATISFIED ??

One last shortcut for you  -> Ctrl + Alt + Shift + K – Shows all the keyboard shortcuts