Thanks ACH! I meant to respond to Cedric's post when I got home the other night... too tired.
Farouk's right... Flash loves to smack people around. "Oh hey Fancy Dan, you wanna adjust those curves in that shape-tween, do ya? Well we're just gonna make the shape DISAPPEAR on you instead. Touche, you and your 'Ctrl-Z', I see you're attempting to adjust from another part of the curve, well let's just shut down the program instead. BYE!"
I don't have anything set up to show... and I stink at the explaining. I'll try to set something up soon; can't just show work stuff of course
Basically within a character you've got layers for arms, hands, body, legs, feet, neck, head... maybe more, maybe less, depending how complicated the character is. It's generally best to keep all the pieces of the character's head (or face, in the case of most Mr. Men & Little Misses who have no separate heads!) within one big nested symbol, so you only have to move that one head/face comp as you move the character around, not move each facial feature individually. Then you can do expression changes & acting within the head symbol.
So that's a bit of something... like I said, I stink at the explaining. I know how it works in my mind, just can't communicate it efficiently/effectively.