If you cannot animate the eyes closing, check that you are not using that blendshape as the Blink Blendshape inside the Avatar's Eye Tracking settings.
Animations cannot animate these blendshapes.
Many avatar bases have a blendshape to close the left eye and the right eye independently. If applicable, you can try animating them both instead in your animation.
Note that disabling eye tracking will let you animate the Blink blendshape, but I discourage doing it because changing eye from Animation to Tracking is instantaneous and will not result in a smooth transition.
Viseme animations when speaking will not work if there is any animation that animates the visemes.
Viseme animation blendshapes should not be used for face expression animations.
If you cannot animate a locomotion pose animation (i.e. Idle animation) or an action post animation (i.e. AFK animation), check that you are not modifying a proxy animation. Proxy animations usually have a name that start with proxy_.
If you are, duplicate that animation, and re-assign it within your animator.
The only purpose of proxy animations is to tell VRChat to replace it with a real animation when the avatar loads.
The avatar's root position will sometime drift away from the actual center of the player as time goes by. This can cause an issue where slightly turning your head would cause the cloth to glitch out of control, as if it was spinning fast.
Add a Position Constraint on your Cloth, and constraint it to the Hip bone of your avatar. This should alleviate the issue.
If your avatar has multiple SkinnedMeshRenderers, you need to make sure the Bounds of all SkinnedMeshRenderers are the same.
In addition, assign an Anchor Override to all meshes of your avatar. You can set the Anchor Override to be a GameObject parented to the Chest or the Hip of your avatar.