hard to explain but here we go
First, begin at a collected trot, horse must be on the bit (if you cannot maintain being on the bit, as the horse will fuss with you when you attempt this that is ok, but do try your best to improve in that area as to achieve a very good mark), with the fence of the ring on your left side
gently, using your body weight, and a SLIGHT turn of the head, go down the center-line from C (or A)
(you will be going to your left, your whip on the right)
at about 3-5 paces, keeping horse collected, and on the bit, making sure your seat bones have an equal balanced weight, and you are sitting perfectly straight in your saddle with your arms gently tucked against your waist, leaning gently back, you must be relaxed for this, as in anything,....
press with your left leg downwards in the stirrup, WHILE your right seat bone presses down on the right side of your saddle
this step, while difficult, is crucial, it takes much practice
while leg-yielding your whip can be gently tapping your horses right hind-quarter, your right foot (with spur is preferable at this stage) gently tapping horse's side (without losing the grip of your saddle and thigh), slightly back than normal, keeping left leg pushed down
DO NOT TURN HEAD OF HORSE TO LEG YIELD!!!!! the horse must remain STRAIGHT, the horse will want to either drag his/her haunches you need to correct this with the equality of your weight and your whip tapping
it is also essential that you look forward, straight forward, not down, but up, and YOUR SHOULDERS MUST BE SQUARE TO THE HORSE'S
the horse needs to be kept at a consistent tempo and maintain good composure and frame (as do you!) you can do this with whip, leg and seat drive
your leg yield, depending on the size of the ring, with a proper Olympic sized ring the leg yield should end at or just before F (starting at C)
at F use body weight to shift back onto the rail and resume
your reins during this must be steady, clam, and remain at your waist
of course, I'm sure you know what a leg yield should look (if not look it up) in terms of what the horses' legs are doing, so remember: the larger the extension of crossing your horse and you perform the higher the marks
this takes much time and practice, remember to reward your horse! it helps to watch yourself in a mirror if you have one and also video yourself to help improve on things
if you have any questions about this or any dressage movement add onto this or add me as your contact and i will look for your questions
i would suggest completing this before your move onto pirouettes
pirouettes require much leg work from both you and your horse during the movement and collected canter, try this first.
i hope this helps you! good luck!
i am currently past the prix st georges level, and would have gone to the olympics next year if it weren't for my schooling