Some studies have shown that skill acquisition is higher using external rather than internal visualization. Lots of visualization in climbing is internal: closing your eyes and seeing your sequence or your hands grabbing the holds. External visualization would be seeing your body, from the outside, as it performed the entire sequence.
To practice this, just perform external visualization on each climb before you start trying it. Try to account for as many details of your movements as possible, thinking about what your entire body does rather than just your hands and feet.
The drill is simple:
1. Close your eyes, and see yourself from outside your body, about to pull on.
2. Notice as many details of what happens while you’re climbing as possible. Notice your posture through the moves, where your head is pointing (gaze)
and the overall quality of your movements. Hear your breathing.
3. Notice any feelings that the visualization brings.
You can do this as much as you want, but I recommend at least doing it for a few climbs per session to practice.
For practice you can also do each climb twice. Visualize internally, to remember the sequence, and repeat the climb. Then, repeat the climb with external visualization. See if you notice anything different between the two styles. For projects you may want to choose one method or the other (internal/external) and stick with it for a session.