Everything is in order of importance
For snakes:
- Head scales, especially from the side, are the most useful.
- A full body shot from the top-side diagonal
- Midbody for scale row counts
For scorpions:
- A full body picture from any angle is useful.
- The back of the last two tail segments.
- The pattern of setae (hairs) on the legs and denticles (bumps) on the pedipalps (hands).
- The pectens (sensory organs) on the underside.