I think so also. I was taught to do head leading except with walk forward ; weight transits between the supporting points (whole flat feet or BTs ).
Depending on what we confirm we are standing absolutely vertically ? The mentions blocks are remarkable different in size and shape. It is hard to be well aware of it .)
Someone said :
the point behind the ear ,shoulder , hip, and foot ( detail points of them ?) in one line . How ? I think it mihgt be a curve line.
When you find your anterio thigh muscle support maximum body weigh and your abdominal and buttock core muscles , pelvic floor are in high tension tone , ?
Put your waist directly , straightly on your hip ?
I tried all the suggestions, sometimes my coach said I moved vertically, sometimes not . The awful things is that I can't differenciate this opposit events by myself.

Yichin1. The imaginary blocks of wood are all the same size. Three in all starting below your rib cage. Then your middle and your pelvis. They must stay one upon the other. none being allowed to go out of line. This centres your control to your stomach area. This is your power house. Extremely tight buttocks and the navel drawn back to the spine is also desirable. There is more if you read Doug's notes. The flexing of the knees at just the right time. The push off the supporting foot, again just at the right time. Your weight still towards your partner even as the leg is at its full extension when going backwards.You will find none of this in a book. In fact when I first started dancing the knees were very straight especially in the Foxtrot. Nobody realized that like an elasic band that is doubled over, the knee now has a lot of energy that can be used. The Foxtrot is the dance where most of this shows up. One more thing. Use the whole of your foot right to the tip of the toe. And I do mean the very tip of the toe. Remembering that the most looked at leg and foot is the one that's behind you. That is enough to last you for several years. As an expert will tell you it may never come, but we can but keep trying.

That's good Don, I never thought of people looking at my back leg in full stride. WE also curl our toes for extra control on some steps.

Dear Don,
It is first time I got a thourough guidance regarding vertical, especially the concept of imaginary wood block to replace the parts of body in varying size and shape, the need of intensive musles contration of the regions of stomach, navel, and buttock, weight center , right use of whole foot , even the extreme toe tips. the energy created from soften knee, the pleasing line of lady's backward leg and foot.
Yes, it will spend my several years to enjoy and practice these vey important techniques with much more confidence . The terrible things is to start in wrong way. Great thanks!
If you have time , please talk more about how the knee ,the elastic band that is doubled over, works.

Yichin 1. Starting at the very beginning. As an excercise stand with the feet together. Put all your weight on the left foot and bend the left knee towards the front. Lift the right foot completely off the floor. Extend back to the very tip of the toe with your right foot, hold onto something if you have to. Bring it back under the body and repeat a couple of times. This time keep the right foot in contact with the floor. After flexing the left knee towards your front send the right foot back to the tip of the toe. Release the weight off the supporting foot and send it back as a complete unit, all the blocks of wood one on the other. Now get a feeling of rolling onto you right foot. Lowering as your weight arrives under your body and not before. If your partner also flexes his supporting knee forewards you should have a joining of the two bodies. If the person going backwards does so off a straight knee you have lost your partner. One more thing and this is important. The ladies backward step is not a mirror image of the mans forward step. Do this with all of the above. Waltz time. Up on the toes count 2 3 and..As 3 touches the floor the right foot should already be on its way back on the count of and. Now push onto the 1 with the help of your partner. If you haven't figured out what I am on about it is .The man starts with his feet together. The lady does not. Done any other way the lady would be pushed onto her step. If its Foxtrot we have a different count.The technique remains the same whether we do one or a dozen steps. One more thing as the man arrives onto his front foot he must flex his left knee forwards towards his partner. And that's only one step. Seriously though, this is the base of most of what you will have to do in the swing dances. It needs to be practised as often as is possible, and that is now and forever.

Dear Don, you are so kind ! I noted all the key points from your post regarding the base to guide my practicing and reviewing.( My printer has been being set for labeling ). Great Thanks!!
My English is out off practice, I am afraid of wrong interpretation about the " off straight knee " in your sentence :"If the person going backwards does so off a straight knee you have lost your partner."
In instance of first Q of feather step, RF backwards,heel leading. Initially, moving leg may close or slightly back with slight natural curve, when left knee is flexing forward then allowing my body gradually off my LF, my right tip toe is sliding backward simutaneously and looked straight than before. Then it has slight curve passively ( lower )due to absorbing weight arriving TB . When my center weight is sent vertically at the supporting points of right TB , I flex my right knee actively to draw the left heel with left side body and head back, flat left foot when it closed RF, down right heel , LF passes RF , back , cross RF , weight trasnfers to LF on second Q. Correct me , if I was wrong.
I was taught to have straight leg as long as possible , my coach said cruved leg is very ugly. So I should avoid to flex my knee before my weight arrived.
off bad is bad, off chance is lost the chance . off white is over white. Does "off straight knee " in your sentence mean the person with no striaght knee when goes backward ? ( over straight knee seems only make sense in Latin.)

Crithen-1. To much technique is worse than no technique at all. Your teacher will give you what technique he or she feels is right for you at the time. You can't learn to dance well from a book. Pay more attention to your teacher and only practice what he or she has taught you, don't jump ahead. Practice less and take more lessons if you can. Learning to dance is about feelings and you get these feeling best from your teacher. John

Dear John, I agree with you : Book or Vedio is for reference ; sportdancing develops quickly as other things. I have lesson with my coache 6 times/ week when he is in Hong Kong. He loves sportdancing very much and always upgrade himself having lesson from top coachings in the world. But it is not enough to me if I can not solo my own part correctly. My coach has been concentrating on my use of standing leg , moving leg ( the tension about it changed in my mind 2 days ago. ) , keeping vertically as well as possible . great footwork, pleasing body line. the ability of following unknown steps .He is absolulely right to emphasize these basic work which enable me to go fast and well; enable me self study because of that I have the basis he given and keep well condition even progress without lesson for 2 more months.( He was surprised so when he returned.) It is not easy for an aged novice. I understood why you say don't jump ahead . The price of bad habit is great . learing new is easier than correct the incorrect thing .I will be very carefully when I am collecting data or practice by myself .
2 weeks ago, we laughed at this idea : I loosed my teeth and becomes weakened but dance very sluggishly on the floor with a thin man with full wrinkle on his face the floor . Some people pointed and said : look at them, they have already danced for 30 years . the lady 89, the man 61. They dance worse than before they had done ...
I told my coach, this future was quite attractive . But 10 years is sufficient to me , It needs less money to support.
I enjoy the whole process of learning sportdancing, a real tough work to dance well . It also improved my figure and health obviously.Be my coach, who should be much more smarter and crazier than me. in such condition I need only to focus on myself doing good job. That 's all.
Any way , I will keep your words in mind to minimize faults. "too" is not good.
If you won't mind , please tell me the meaning of " off straight knee " in the sentance of "If the person going backward does so off a straight knee you have lost your partner. (I put it on the dictionary .com yesterday. The translation may not make sense.)

He's suggesting that when lowering to move backwards you want to allow the standing knee to first bend slightly forwards. It will of course straighten again as your body moves away from the standing foot.

Yichen1. I only just caught up with this question. If as you step backwards and you dont flex the knee towards your parner. You will either go nowhere , which we might expect from a beginner, or you will fall back, prematurely lowering. The front leg will straighten and your toe will lift to the ceiling. All caused by the incorrect use of the knee.