Simple Eye Wink Animation

First thing I would try is just to quickly scale the Y parameter to zero and back.  Blinks are fast

and the quick vanishing & reappearing of the image is usually enough to trigger the viewers brain into believing they've seen a blink. They will not even notice the odd distortion caused by scaling in Y.  It will be too fast to see.

The most basic animation for this will be to turn the opacity randomly on and off.

I used to use an expression for the random blinking from Dan Ebberts:

minSeg = 2.0;
maxSeg = 5.0;
blinkDur = .5

seedRandom(index,true)
segStartTime = -random(minSeg,maxSeg);
segEndTime = segStartTime;
i = 1;

while (time >= segEndTime){
   i += 1;
   seedRandom(i,true);
   segStartTime = segEndTime;
   segEndTime = segEndTime + random(minSeg,maxSeg);
}

if (time > segStartTime + blinkDur){
   0;
} else {
   100;}

A more sophisticated solution would be to add an artwork of the closed eye. You can put the above expression to the "open eye" artwork opacity and put this expression to the "closed eye" artwork opacity:

100 - thisComp.layer("OpenEye").opacity;

If your artwork is named differently, use the pigwhip.

This code will show the "closed eye" artwork whenever the "open eye" artwork is not shown.

Of course you can use keyframes to animate this all, but learning expression will safe a lot of time on the long run.

*Martin