In this video, Signe breaks down the loop jump for skaters who are just starting to learn it.
Pre-requisite: Back scratch spin
The entry Signe recommends is the forward inside three turn, which is the most common way to begin to learn it.
Signe emphasizes the importance of having the arms counterchecked when entering into the forward three turn to have a good body alignment and position for the take-off. She shows a few exercises to work on the H position, and highlights how the hips need to be internally rotated.
She also explains that the loop jump is more of an advanced jump from the waltz, salchow, toe loop because it requires a higher level of control and edge quality on entrance to be able to have a clean take-off rather than having a swingy entrance and an underrotated loop jump.