Shapekey-related

My custom shapekeys (body shape, lipsync, etc) won't save properly / display ingame!
If importing custom animations from Blender, make sure that they don't have junk keyframes assigned for shapekeys in the Animation panel.
Make sure the body mesh selected for the visemes/blink is properly dragged-and-dropped from the hierarchy.
When exporting from Blender, make sure that the geometry tab of the export settings looks like this, with Apply Modifier unchecked:
In the Animator panel for the gesture controller, if applicable, make sure that the weight is set to 1 and that the override is properly set (or in some cases not set):
My lipsync isn't working / the mouth is frozen open!
Check the section above and make sure 'Apply Modifiers' is unchecked in the FBX export settings in Blender.
Make sure all animations (idles like tail swishing or arms to the sides) exclude blendshapes. You can delete keyframes easy enough.
Make sure when you set your body mesh that you are dragging from the hierarchy and NOT the assets section!
The body should be labeled Body (case-sensitive).
Idle anims (tail wagging) need Loop Anim (not pose!) and Write defaults enabled.
If you imported animations from Blender, duplicate them (after setting up avatar) and remove the shapekey frames. 
If your character's mouth is open in T-Pose, make sure the 'sil' viseme is at 100 in the Body mesh settings.