List of common AE-Shortcuts

⌘++⇧+Ynull-object

The Y’s:
⌘+Y new solid
⌘+⇧+Y solid settings
⌘++Y adjustment layer
⌘++⇧+Y null object
Properties:
P Position
R Rotation
S Scale
A Anchor point
T OpaciTy… (or Transparency)
U show/hide every animated property of selected layer/s
UU (U tipped twice) show every changed property of selected layer/s
Layers:
⌘+D duplicate layer
⌘+⇧+D duplicate layer and cut at Current-Time-Indicator
⌘++T enable Time-Remapping
RR (R tipped twice) Time-Remapping property (only when applied)
+[ trim in-point of layer
+] trim out-point of layer
[ move layers in-point to Current-Time-Indicator
] move layers out-point to Current-Time-Indicator
Navigation:
⌘+←→ move Current-Time-Indicator by 1 frame
⌘+⇧+←→ move Current-Time-Indicator by 10 frames
+←→ move selected keyframe/s by 1 frame
+⇧+←→ move selected keyframe/s by 10 frames
I jump to In-point of layer
O jump to Out-point of layer
Playback:
space-bar play/load into RAM from Current-Time-Indicator
ctrl+0 play/load into RAM from the beginning of the Work Area
ctrl+. play sound only
⌘+scrubbing scrub + play audio
Others:
⌘+M / ⌘+ctrl+M “Make Movie”/”Add to Render Queue”
B set Beginning of Work Area
N set eNd of Work Area
M Mask Path Property
MM (M tipped twice) show all mask properties
F Feather of mask
⇧+Number set a (Composition-)Marker
ctrl+8 create Layer Marker (also works during playback)