I love collecting images of expressions. I have several modelling books dedicated to the subject in my library. Most expression sheets and therefor gigs tend to look for the obvious expressions:
(Here are some wonderful Spongebob expressions, executed masterfully)
But I saw this one online and have often struggled to feel that the normal looking characters get to express themselves. Thought I'd share the image and link to it.
Keep in mind that experience outways reference. Reference is there to remind you. It's like if you pick a knife up by the blade, instead of the handle and cut yourself, the next time you need to pick up a knife you are reminded more accutely which end to use;)