Creating Shape Keys +—

1. Create a model to be morphed
2. In the "Object Data Properties" (where vertex groups are accessed), click on the "+" next to "Shape Key" - this creates a "Basis" shape - the default state of the mesh without any keys
3. Make the first shape key:
   1. Click on the "+" again to create the first keyframe
   2. In "Edit mode", adjust the vertices to an initial position as needed (if different from the basis shape)

Additional Shape Keys from Basis Shape +—

1. Back in "Object mode", in the properties panel, click on the new shape key button "+"
2. In "Edit mode", adjust the vertices as needed to make change the shape
3. Repeat these steps as needed

Creating New Shape Keys from Existing Keys +—

1. In "Object mode", back in the properties panel, in the shape key area, uncheck all shape keys except for the key to copy
2. Make sure the key to copy is selected
3. Click on the "⌄", below the add/remove buttons to open the shape key menu
4. Click on "New Shape From Mix"
5. In "Edit mode", adjust the vertices as needed to make a new shape
6. Repeat the previous steps as needed

Animating Shape Keys +—

1. In the Playback Timeline navigate to the frame for the first keyframe (ie. frame 1)
2. In the "Object Data Properties" make sure that all shape keys that will be part of the animation are checked
3. Set the value for the Shape Key that should be visible to "1" and click on the diamond to make a keyframe (or hover over the number and press "I")
4. Set the value for all the other keys to "0" and set keyframes for each key
5. In the Playback Timeline navigate to the frame for the next keyframe
6. Set the value of the first shape key back to "0" and set a keyframe to save the change
7. Change the value for the next shape key to "1" and set a keyframe to save the change
8. Scrub or play through the Playback Timeline to see the transition
9. Repeat as needed