Preferences:
-Use cash for histogram>>to generate a histogram using all pixels in the image. Shift + histogram.
-To get a protractor, with the measure tool selected + alt.
Save for the Web:
In the Save for Web Dialog, click on the right-facing arrow that is to the right of the Settings pop-up menu. Click and hold it. When the menu appears, select Optimize to File Size, then just enter the file size you want your document to be.
Fade Command:
Use the fade command to fade the liquify, extract, color adjustment.
Full screen Mode:
Place your images in the desired stacking order and then, shift + click on the full screen mode>>ctrl+tab to show them.
Batch Command:
In the automate batch command if you checked the ?override action ?open? commands? the action will effect on batched files and not on unopened files ?files names?.
Palette Well:
You can park your palettes compilation In the right section of the option bar (at least 800x600),. Simply drag palette to that section and you?ll end up with a number of palette that you frequently use.
-To apply a blur filter on the edge of a layer, be sure to deselect the preserve transparency option.
-Apply the filter on individual channels in case of insufficient memory.
Ammar
useful ones 
Linear Mode
