Using Shortcuts will save our time. Here is some useful photoshop shortcuts:

1- Create a New layer: Ctrl+Shift+N
This shortcut creates a newlayer over the current active layer.
Create a new layer: Ctrl + Alt + Shift + N
This command will make a new layer without dialog box.

2- Copy merged: Ctrl+Shift+C
For copying layers merged. This command copies all layers within the selection as a single layer.

3-Merge all visible layers: Ctrl+Shift+E
This will Merge all the visible layers.

4-Increase Brush size: ]
pressing ] key will increase the brush size
This can be used to change size of brush, Eraser, Clone Stamp etc.

5-Decrease Brush size: [
pressing [ key will increase the brush size

6-Change brush Softness: Shift+] and Shift+[

Shift+] for increase softness by 25% and Shift+] for decrease softness by 25%

7-Tool Opacity: This can be changed by Using the no keys 1 to 0 will change opacity from 10% to 100%

8-Zoom to 100%: For making Zoom 100%, Double click on the Zoom tool

9-Hiding All other layers: Alt + click in the Layer show/hide button of the required layer.

10-Transforming Proportionally: Shift + dragging from corner will transform object proportionally