Maintain stroke width when scaling

Apply this expression to the Stroke Width property of any shape layer to maintain the visual thickness of the stroke, no matter what scaling is applied to the layer.

value / length(toComp([0,0]), toComp([0.7071,0.7071])) || 0.001; 

LoopOut for After Effects Paths

 LoopOut does not work for path layer animations. Use this instead:

if (numKeys > 1 && time > key(numKeys).time){
  t1 = key(1).time;
  t2 = key(numKeys).time;
  span = t2 - t1;
  delta = time - t2;
  t = delta%span;
  valueAtTime(t1 + t);
}else
  value

Rendering PNG Sequences with Alpha Transparency

Exported PNGs rendering as not transparent?

In the render queue, go to Output Module > Video Output > Channels > RGB + Alpha

Render After Effects Shadows on Transparent Layers

I stole these instructions from a Creative Cow Forum post. 

Start with
Some comp with a 3d character or something that you want to cast shadows.
New White Solid. 
Make it 3d. 
Make a light. 
On your character set the material options to Cast Shadows and not to accept light or shadows. 
Set the white solid to accept shadows, not lights and not cast shadows. 
Position in the scene as a floor and Pre-Comp as Floor.
Collapse Transforms
Inside Floor comp set mode to Silhoutte Luma
Back in the main comp make sure you have some background behind the floor. (Black Solid will do it)

The Siloutte Luma will cut into the Black Solid giving you transparency with just a shadow. If you need other parts of your scene rendered just go back into the floor clip and create more white solids to take up space.

Your layers should look like this
Main Comp
Light
Character
Floor Precomp
Black Solid

Floor Comp
White Solid for Floor (blend mode set to silhoutte luma)
Other Solid for wall (if desired)
...

Global Variables to Determine Color

I had a project where I needed to set specific objects throughout all my comps to global color values.

1. Create a comp called globalVars and add a null layer named globalVars
2. In this layer add a Color expression control and set to desired color. Name it Color1.
3. In another comp select a layer and add a Effect>Generate>Fill effect
4. Set the filled layer to this expression: comp("globalVars").layer("globalVars").effect("Color1")("Color")

Color Management in After Effects

Here is a great tutorial on Creative Cow that explains color management in After Effects very well.

http://library.creativecow.net/articles/devis_andrew/Assigning-colour-profile/video-tutorial

Smooth Credit Rolls in After Effects

To remove the jitter from scrolling text, the next needs to be set at 80% transparency (so it isn't so harsh), and moved in whole-pixel increments.

This amazing template makes it super easy. Just open the AEP, select your desired format comp, past in your roll art, and parent it to the null.

Silky smooth.

http://www.reduser.net/forum/showthread.php?58688-Silky-smooth-credit-rolls-in-After-Effects