Exaggeration, and usually much more roundness. For Western, at least.
Eastern are usually those niche faces that you can actually do in emoticons, like -__- and stuff.

Hmm, sounds good though I think that's my weakest point- I believe I will have to learn a completely freehand way of making the head to exaggerate that much and I've almost always used a set frame to build them -n-;;;

This is advice I could use, I'm glad you posed this question ^^

We might need a much more 'high traffic'(aka popular) artist to pose the question before the answers start rolling in though ^o^;

Watching Tex Avery cartoons for western and maybe old 80s anime for eastern.

A lot of cartoons watched on my childhood were my influences.

I have not seen any tutorial even about those kind of expressions.

Thanks for the advice cousin, with the right search terms I believe youtube will provide some resource material ^u^

Don't be afraid to do things that simply don't make sense anatomically. In Western cartoons, eyes that extend beyond the borders of the head by even a little bit indicate surprise, and of course there's the ever-famous jaw-to-the-floor technique. I would suggest Rocko's Modern Life for examples of utterly outrageous facial expressions ( http://www.lulz.ro/pics/12606536888.jpg ).
In Eastern stuff, particularly anime, wacky expressions are achieved more through changing the shapes of things (eyes and mouth in particular), but not necessarily the size (although that happens at times too). http://blog.peoplesdns.com/screens/perverted.png

Those are some guidelines I've picked up myself, although I don't implement them except in certain situations. I guess the biggest thing is: Throw out what you know about facial anatomy and do what looks hilarious.

Thank you, I'll keep those things in mind ^u^

Hope it helps!

Working on it -nodnod-

i think probably just lookign at Donald Duck, Goofy, Mickey Mouse, and those kind of cartoons woudl help for bas, they usually have good expression =3
there is also a cartoon called "Bonkers" that could be excellent, its all about extreme toon http://www.youtube.com/watch?v=CbqFGapihP0

Thanks nephew, I'll look into that ^u^

Maybe the Eastern is more of a round-shape head like chibis o.o

I'll keep it in mind.