I was lucky enough to attend "The Art of Physical Touch" workshop at Core Sport lead by Simona Cipriani whom was taught by Romana. Pilates is all about stretch, strength and control. Working hands on with your clients will encourage or help in correcting their movement patterns. Make sure you ask permission and know your client well before moving into touch techniques. Also keep in mind to use props such as a wooden pole or strap for the feet. As Joe would say, "You feel it where you need it," and touch can assist in taking you deeper into the system.
The skin is the largest organ in the body with receptors that can determine heat or cold, soft touch, vibration or pain. Certain body parts such as the hands and lips have more of these receptors than a knee or elbow. Keep in mind to use your thigh and hands depending on the exercise. Below are some examples of useful touch in matwork:
100s/Ab Series: support the upper back/shoulders with heel of the hand or palms to get into the full C curve, spot feet at heels to activate more glute/hamstring or ensure proper tracking of legs
Roll Up/Spine Stretch Forward: feet in loops to ground heels, weighted pole to assist the Roll Up, wooden pole to "roll out the pizza dough" on low abs for Spine Stretch
One Leg Circles: stabilize hips or shoulders with heel of hands, press hand into bottom thigh to help squeeze when circling
Rolling like a Ball/Seal: from the front of the mat slide your foot under client on the roll back so thigh supports the bottom on the balancing point then take away to roll back up
Side Leg Series: straddle the waist with both feet to keep torso steady, line up a wooden pole on the top thigh to keep leg in alignment, palm of hand on top heel to activate more inner thigh
Teaser: thighs help balance the legs in classical Teaser position, client presses tops of hands into your palms to assist rolling up