Here is handy set of shortcuts to keep in mind when you're working with transform properties in AE.
(Shortcuts in parenthesis are the Window equivalents.)

Working with properties :

A-Anchor Point

P- Position

S-Scale

R-Rotation

T- Opacity

To add/subtrack - Shift+property solo key

Show all animating properties - U

Reveal modified properties - UU

Solo selected properties - SS

Hide property or category -
Option+Shift(Alt+Shift) + click property or category name

Selectal all keyframes for that property -
click property name

Turn on property stopwatch -
Option+Shift(Alt+Shift) + respective reveal key

If stopwatch on, add/delete keyframe -
Option+Shift (Alt+Shift) + respective reveal key

Set value in dialog box -
Command+Shift (Control+Shift) + P,S, or R

Constrain Scale to aspect ration -
Drag layer handle to start scaling, then add Shift

Constrain Rotation to 45 degree increments -
Rotate with tool, then add Shift

Reset Scale to 100% - double-click selection tool

Reset Rotatoin to 0% - double click rotation tool

Nudge Scale + 1% and -1% -
Option+(Control+) and Option-(Control-) (plus and minus keys) on the numeric keypad (add shift to scale plus/minus 10 degrees)

Nudge Rotation + 1% and -1% -
+ and - on the numeric keypad (add shift to rotate plus/minus 10 degrees)

Stretch layer to fit Comp size - Command+Option+F (Control+Alt+F)

Stretch layer to fit vertically only - Command_Option_Shift_G (Control+Alt+Shift+G)

Stretch layer to fit horizontally only - Command_Option_Shift_H (Control+Alt+Shift+H)

Controlling the Timline

Create a comp - Control+N

Place a comp marker - Shift+#

Move a layer to 00:00 - Alt+Home

Move a layer to end of comp - Alt+End

Import a file - Control+I

Open composition settings - Control+K

Add selected source to top layer in current composition - Control+/

Open Interpret Footage dialog - Select footage in Project window and type Control+F

Zoom in comp - ,

Zoom out comp - .

Deselect all layers - F2

Return to 00:00 - Home

Return to end of comp - End

Bring up Go to Time dialog - Control+G

Move In point of layer to CTI(Current Time Indicator) - [

Move Out point of layer to CTI(Current Time Indicator) - ]