Here's one for those struggling with facial expressions. Both resources are detailed and well put together. Hope you enjoy!

Joumana Medlej, has created a huge chart, detailing the key signs for different moods. Better still, they are nicely grouped, so if your expression doesn't quite say what you want it to, check the chart and it will provide great pointers for which areas to push and pull.
To view the chart, please click on the picture or cedarseed.com to visit the website
Lackadaisy's 'Notes on Expressions'

The cartoon strip is a goldmine, illustrating how choice of expressions can be dependant depending on the personality of the character.
To visit the Lackadaisy, please click on the pic. Thank you