Bring yourself to a strict push-up position
Maintain a toe placement roughly at shoulder width (the wider the leg stance the easier the exercise - the narrower the stance the more difficult it becomes.
Tap your opposite shoulder with your fingertips.
Do not tilt or shift your hips. Do not round or arch your back.
Guía de Ejercicio Core Stability 4 Crosslateral Limb Raise Push Up Position - Entrenamiento de Abdominals | MuscleWiki