Before importing your avatar to Unity, make sure the head and body are merged and use the name 'Body'. This is important if you want to add face tracking!
Click on the fbx file of the avatar in Unity and make sure "Legacy Blend Shape Normals" is checked under the 'Model' tab.
Making a quest version? For transparents, you can use the following shader:
"VRChat>Mobile>Particles>Multiply"
How to add face tracking to your avatars: