When learning any sort of physical skill like dancing it certainly helps if you understand the basic principles of movement. It is useful to view the body, an in particular the sensori-motor system that controls posture and movement, as organised so as approach, grasp and manipulate an object. To understand this lets can look at what happens when you execute a simple action of picking up an object such as an apple. Lets say you are looking for something to eat. The eyes scan and immediate environment and recognising an apple. Focusing on the apple then you will tend to face it and turn the body and move in the direction of the apple. You reach for the object and grasp it with your hand. The body braces itself anticipating the weight of the object.
The body follows the extremities: (i) the gaze and head; (ii) the arms and legs. It follows and adjusts to movement that is initiated from these extremities. While you normally use the lower extremities to connect to the ground and walk you can use them in a similar manner to arms/hands to reach and manipulate things, eg., to move objects and the body will reorganise to allow that to happen.
The main difficulty in dancing tango is that you cannot use the orienting mechanisms that operate in your ordinary life: you do not always walk forward but often backwards or around; you have a partner in front of you; and you cannot look at the feet because this is detrimental to the embrace so that you lose connection with your partner and no longer move through space as a single unit.
While show dancers can be seen to look around and move their arms to direct their movement, in tango estilo milonguero you are in a tight and unchanging embrace. Your eyes and hands are not available to initiate and orient movement. All the movement is below the waist, in the legs and feet.
So you have to learn to orient yourself without using the eyes. In that sense you are virtually blind and need to use a different mode to scan the environment. In tango, you shoul use your feet to scan and orient the direction of the movement, and also to communicate direction to your partner. Movements of the feet that many consider merely decorative choreography are actually functional scanning and orienting movements and are therefore emergent.
To orient the movement feet have to open up and the differing angle between the feet orients the body.* The direction of the free foot orients the body in a new direction as you move into that foot and put weight on it. This information is then transferred to your partner: as the man orients the foot and moves his weight onto that foot the woman will be naturally drawn in that direction, and as the woman then moves into the next foot this information is registered by the man.
The orientation of the foot is the pointing with the toe when moving forward or with the heel when moving back. The foot works a bit like a rudder in a boat: it is oriented in the requisite direction and then the whole moves in the direction. However, it is not obvious how the direction of the rudder/foot affects the direction of the movement and so some explorations help us to coordinate your movement so that you learn, as with learning to drive a car or steer a boat, how your foot movement affects the direction of the movement of the whole couple. Moreover, you need to learn to do this without looking at your feet.
One way you can do that is with the help of an imaginary clock. The centre of the clos is between the heels. The feet are the two hands of the clock. Lets say the left foot is the big hand and the right foot is the small hand. If you point both toes forward this is 12 o’clock. If you point the feet out that’s 11.05, 10.10, and 9.15 which would be like a ballet dancers turn out. Normally you will keep one foot/hand still and the other foot/hand will turn.
The normal starting position is 11.05 and so this is your point of reference. You will never be at 12 o’clock. To turn right you will move to 11.10 by drawing the heel/knee up and then dropping the foot in the new position. When you then draw up the right foot you will be in the new position and thus return to 11.05. To turn left you draw up the left heel/knee and drop it at 10.05, and then follow that with the right foot to return to the neutral position. Always practice these movements with good posture and alignment, floating your head on top of your spine.
*In some styles of tango feet point forward so that to turn it is necesssary to swivel. Swiveling is not an efficient way to move or turn (see Turning). While it looks aesthetically pleasing and allows for large expressive movements with large hip movement, it is inherently unstable and requires a level of strength and athleticity that is not suitable to social dancing and is not an efficient way of moving will lead to fatigue. Finally, it is completely at odds with the requirements of the sustained close embrace. So because you do not want to swivel and you want the hips to remain relatively square to the shoulders and always facing the partner, you need to free up the feet.